FIELD OF INVENTION

The present invention relates to a semi-automatic pipette filler instrument, which is economical, compact, lightweight, having less repetitive stress injury in handling and provided with ergonomic features. Particularly, the semi-automatic pipette filler (SAPF) is capable to operate not only by normal human being but also by handicapped people especially wheelchair bound. The said modified / improved pipette instrument is having utility for teaching and research laboratories, small scale and large scale industries.

BACKGROUND AND PRIOR ART OF THE INVENTION

It is known that for any volumetric analysis, pipettes (5, 10, 20 or 50 ml) and burettes are having significant importance. A liquid can be poured from the top into a burette with the help of a funnel, but a pipette cannot be filled up in a similar fashion and the liquid has to be sucked up the pipette from the bottom. This is a tricky part. Many pipette users simply suck with their mouth and then adjust the level of the sucked-in liquid in the pipette to a desired mark with a finger, which calls for good hand-mouth coordination.

For a beginner this can be frustrating. Once the dexterity is attained the conventional technique is simple and effective but use of mouth for filling pipettes could be risky if the liquid being sucked is toxic/corrosive in nature and if it inadvertently gets sucked into the mouth. In some cases, the toxic/corrosive liquid might not get into the mouth, but its vapour can cause harm to the mouth.

From personal hygiene aspect, it is undesirable to use mouth for common laboratory apparatus to reduce the risks of contacting communicable diseases. Hence sucking a liquid into a pipette by mouth has to be eschewed from personal safety consideration. As a matter of fact, in spite of the hazards involved, students in many high schools, colleges and institutions across the country and abroad, use their mouth for experiments involving pipette. As a consequence some of the students wary of either chemicals getting into their mouth or apprehensive of contacting some communicable disease by mouth, perform chemistry laboratory practical' s/ experiments involving pipette work with some trepidation which to certain extent affects their performance.

To overcome this problem, safety pipette fillers are developed and are commercially available. The various types of pipette filling devices known are: the simple bulb, 2-3 valve pipette filler, the pipette pump and the pipette controller. Amongst them the bulb type is awkward to use. A manual 2-valve safety pipette filler from Deutsch & Newmann (D&N, Germany) used in USER Mohali is shown in figure 1.

However, most schools and colleges in India and other developing countries cannot afford commercially available pipette fillers owing to their comparative prohibitive cost. The pipette pump is available for dispensing 10 ml and 25 ml of liquid costs Rs. 450 and Rs. 650 per piece respectively. The pipette controller costs Rs. 2200. The cheapest commercially available manual pipette filler like the one shown in figure 1 costs approximately Rs.400 per piece. They also have to be replaced quite often as they stop working satisfactorily after a while for the following reasons:

(i) These pipette fillers work fine as long as they are pressed exactly on the spots marked (†,j) on them (figure 1). Pressing on any other place deliberately or inadvertently damages the pipette fillers as ball sockets get dislocated and are not easy to fix.

(ii) Many a time due to confusion, wrong pressing of the spots (†, j) (figure 1) results in liquids overflowing into the natural rubber from which the pipette fillers are made resulting in its malfunctioning. Although there is a provision to clean them by removing the white plug at the top, but it is a tedious job.

(iii) The pipette fillers do not have a long shelf life as the natural rubber tends to undergo deterioration on exposure to air and light which renders the pipette fillers useless and dispensable.

Figure 39 shows a pile of dysfunctional D&N pipette fillers. Even for well-funded institutions, finding a quick replacement for defective/dysfunctional pipette fillers is not easy. Besides the usual paperwork required for ordering of expensive pipette fillers, there is considerable delay involved in procuring them even after the order has been placed. This is because local laboratory dealers do not stock such expensive imported lab wares in large numbers because of low demand, price fluctuation depending upon the strength of Indian rupee in the international market, and the limited shelf life due to natural aging of the product as mentioned earlier.

Hence a need is felt to develop an improved pipette instrument that is affordable, long lasting, user-friendly (for both able bodied and handicapped), easy to operate & maintain, with low risks of repetitive stress injuries (RSI) and above all accomplishes the task just like its imported counterpart.

OBJECTIVES OF THE INVENTION

The primary objective of the present invention is to provide a semi-automatic pipette filler (SAPF) instrument is economical, compact, lightweight and having less repetitive stress injury in handling and provided with ergonomic features.

Yet another objective of the present invention is to provide a modified or improved pipette having less repetitive stress injury in handling and provided with suction pump.

Another objective of the present invention is to provide a pipette arrangement comprising a pipette (P) connected with at least one semi-automatic pipette filler (SAPF) instrument.

Yet another objective of the present invention is to provide a pipette arrangement comprising a pipette (P) connected with at least one semi-automatic pipette filler (SAPF) instrument, which can be operated not only by normal human being but also by handicapped people especially wheelchair bound.

Yet another objective of the present invention is to provide a kit of semi-automatic pipette filing instrument.

SUMMARY OF THE INVENTION

The present invention relates to a semi-automatic pipette filler (SAPF) instrument, and an improved or modified pipette with suction pump, which is semi-automatic, economical, compact, lightweight, safety pipette filler with ergonomic features designed. The SG-IM semi-automatic pipette filler (SAPF) has been tested for both graduated and volumetric pipettes of various sizes and can perform multipurpose tasks. It has been compared with the commercially available imported safety pipette fillers commonly used in various teaching and research laboratories in India and abroad. Handicapped people especially wheelchair bound users will find some of the designs rather convenient to use compared to commercially available ones. The SG- IM SAPFs can be quickly assembled and dismantled. The overall performance of SG- IM SAPFs has been very encouraging. Since pipettes are widely used in large numbers in educational, quality control and research laboratories there is considerable incentive for small scale industries to mass produce SG-IM semi-automatic safety pipette fillers (SAPFs).

Further aspects and advantages of the present invention will be readily understood from the following detailed description with reference to the accompanying figures.

The figures together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present invention wherein:

BRIEF DESCRIPTION OF FIGURES

Fig. 1 shows prior art of a two valve manual rubber pipette filler.

Fig. 2 depicts various parts of commercial available syringes.

Fig. 3 shows cross section view of rubber tubing connector according to one aspect of the present invention.

Fig. 4 (a) shows SG-IM Pipette Filler Design 1 according to present invention; (b) shows D&N manual rubber pipette filler as per prior art.

Fig. 5 shows holding of SG-IM Pipette Filler Design I according to present invention Fig. 6 exhibits dispensing of Liquid by Mode 2 using SG-IM PF Design I according to another aspect present invention.

Fig. 7 shows the SG-IM Pipette Filler Design II according to another aspect present invention.

Fig. 8 shows handling SG-IM Pipette Filler Design II according to another aspect present invention. Fig. 9 depicts SG-IM Pipette Filler Design III according to another aspect present invention.

Fig. 10 shows holding SG-IM Pipette Filler Design III according to another aspect present invention.

Fig. 11 shows SG-IM Pipette Filler Design IV according to another aspect present invention.

Fig. 12 shows SG-IM Semi-Automatic Pipette Filler (SAPF) Design V according to another aspect present invention.

Fig. 13 shows shielding of rubber tubing with PVC tube according to another aspect present invention.

Fig. 14 exhibits dismantling of PVC tube according to another aspect present invention.

Fig. 15 illustrates Cross-section view of a segment of SG-IM SAPF Design VI according to another aspect present invention.

Fig. 16 shows SG-IM Semi-Automatic Pipette Filler (SAPF) Design VI according to another aspect present invention.

Fig. 17 shows handling of SG-IM Semi-Automatic Pipette Filler Design VI according to another aspect present invention.

Fig. 18 illustrates dispensing liquid by Mode 2 using SG-IM Semi-Automatic Pipette Filler (SAPF) Design VI according to another aspect present invention.

Fig. 19 shows assembling SG-IM Manual Pipette Filler Design VII according to another aspect present invention.

Fig. 20 shows assembling SG-IM Manual Pipette Filler Design VII according to another aspect present invention.

Fig. 21 shows SG-IM Manual Pipette Filler Design VII according to another aspect present invention.

Fig. 22 depicts SG-IM Semi-Automatic Pipette Filler Design VIII according to another aspect present invention.

Fig. 23 illustrates Handling of SG-IM Semi-Automatic Pipette Filler Design VII (SAPF VII) according to another aspect present invention.

Fig. 24 shows SG-IM SAPF Design IX according to another aspect present invention. Fig. 25 exhibits SG-IM Semi-Automatic Pipette Filler Design VIII & IX according to another aspect present invention. Fig. 26 shows SG-IM Pipette Filler Design X using 20 mL Syringe according to another aspect present invention.

Fig. 27 shows SG-IM Universal SAPF Pipette Filler using 50mL Syringe according to another aspect present invention.

Fig. 28 Graduated Pipette (10ml) attached to SG-IM SAPF design VI according to another aspect present invention.

Fig. 29 illustrate after dismantling assembly as shown in Fig. 28.

Fig. 30 shows commercial Manual D&N and SG-IM Semi-Automatic Pipette Fillers according to another aspect present invention.

Fig. 31 (a) D&N 2- valve manual pipette filler (b) SG-IM SAPF Design XI according to another aspect present invention.

Fig. 32 shows holding SG-IM SAPF Design XI in Vertical Position according to another aspect present invention.

Fig. 33 shows holding SG-IM SAPF Design XI in Horizontal Position according to another aspect present invention.

Fig. 34 shows holding SG-IM Pipette Filler Design XI in Vertical Position according to another aspect present invention.

Fig. 35 shows holding SG-IM Pipette Filler Design XI in Horizontal Position according to another aspect present invention.

Fig. 36 shows SG-IM Semi-Automatic pipette Filler Design XII according to another aspect present invention.

Fig. 37 shows holding of SG-IM SAPF Design XII according to another aspect present invention.

Fig. 38 indicates position of Fixed Screws with respect to each other according to another aspect present invention.

Fig. 39 shows dysfunctional D&N Manual 2 valve Rubber Pipette Filler according to another aspect present invention.

Fig. 40 shows SG-IM Semi-Automatic pipette Filler Design XII according to another aspect present invention.

Fig. 41 shows SG-IM Pipette Filler Design XI in Horizontal Position according to another aspect present invention.

Fig. 42 shows International Symbol of Access (ISA) can be given to SG-IM Pipette Filler Design XI in Horizontal Position since its best suited for even wheelchair bound people according to another aspect present invention. Fig 43 shows SG-IM Semi- Automatic Pipette Filler (SAPF) Design VI.

Fig 44 shows SG-IM Semi- Automatic Pipette Filler (SAPF) Design IX.

Fig 45 shows comparison of the pipette filler of the prior art and pipette instrument according to the present invention.

Fig 46 shows semi-automatic pipette filler (SAPF) according to the present invention.

Fig 46(a) shows another aspect of the present invention.

Fig 47 shows a pipette arrangement according to the present invention

Fig 47(a) shows another aspect of the present invention.

Fig 47 (c)-(d) shows connectors according to the present invention

Fig 48 shows a pipette arrangement for a person on wheel chair or of short height according to the present invention.

Fig 48 (a) shows another aspect of the present invention.

Fig 49 shows a modified pipette according to the present invention.

Fig 50 shows a kit of pipette filing instrument according to the present invention

Skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.

DETAIL DESCRIPTION OF PROPOSED INVENTION

While the invention is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the figures and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention as defined by the appended claims.

Before describing in detail embodiments it may be observed that the novelty and inventive step that are in accordance with the present invention resides in an improved pipette instrument. It is to be noted that a person skilled in the art can be motivated from the present invention and modify the various constructions of pipette instrument assembly. However, such modification should be construed within the scope and spirit of the invention.

Accordingly, the drawings are showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device, instrument panel that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such setup or device. In other words, one or more elements in a system or apparatus proceeded by "comprises... a" does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus. The following paragraphs explain present invention. The invention in respect of the same may be deduced accordingly.

In the present invention, the expression "suction pump" intended to cover an assembly of plunger and suction chamber, and/or a syringe. The expression "assembly of plunger and suction chamber" and "syringe" are interchangeable for the understanding of invention.

Accordingly, the present invention relates to a semi-automatic pipette filler (SAPF) instrument for pipette, comprising at least one assembly of plunger (1) and suction chamber or barrel (2), wherein the assembly comprising a plunger (1) and reciprocate inside the barrel (2), the barrel having an inlet port (2i) and outlet port (2o) and at least one aperture ( 3) on the body, a threaded spacer (4) is being configured inside the barrel (2) along the plunger (1), the threaded spacer (4) is being adapted and accommodated in the space available in the plunger (1) so as to reciprocate along the plunger (1), the threaded spacer is being provided with means (5, 6) to adjust the displacement of the threaded spacer (4) and plunger (1) inside the barrel (2), a pair of safety means (7, 8) are provided with elastic members (12,13) at the outlet port (2o) of the barrel (2) that are being in contact with the plunger (1). One aspect of the present invention, wherein the barrel (2) is made of plastic and plunger is made of elastomeric material.

Another aspect of the present invention, wherein the barrel is having inlet port (2i) is either centrally placed or offset from the centre.

Yet another aspect of the present invention, wherein the inlet port (2i) of barrel is preferably in the shape and size of pipette outlet (PO).

Yet another aspect of the present invention, wherein the plunger (1) is having V-shape grooves (11).

Yet another aspect of the present invention, wherein the threaded spacer (4) is a bolt with thread and being provided with double nut system (5,6) and mounted with plunger with elastic member (9).

Yet another aspect of the present invention, wherein the double nut system (5, 6) comprising one big nut (5) and one small nut (6) and located outside the outlet port (2o) of barrel.

Yet another aspect of the present invention, wherein the big nut (5) displace by sliding to and fro along the length of the threaded spacer (4) to any extent on threaded spacer and locked by the smaller nut (6) at any desired location on the threaded spacer.

Yet another aspect of the present invention, wherein the small nut (6) displace along the length of the threaded spacer (4), upon rotating clockwise or anticlockwise around the longitudinal axis of the threaded spacer.

Yet another aspect of the present invention wherein the big nut (5) comes in contact with barrel outlet port (2o), while plunger (1) is pushed inside the barrel (2) and thereby achieve desired plunger movement inside the barrel.

Yet another aspect of the present invention, wherein the double nut system (5,6) along with the threaded spacer assists to fill the pipette in a pre-determined manner to any meniscus level. Yet another aspect of the present invention, wherein the meniscus levels is predefined and vary in the range of 1 ml to 50 ml.

Yet another aspect of the present invention, wherein the safety means are two screw (7,8) with or without thread with rubber sleeve (12, 13) and positioned at 180° to each other at the inner side of the outlet port of barrel.

Yet another aspect of the present invention, wherein the safety means (7,8) prevent the plunger from being inadvertently pulled out of the barrel and loss of suction, while the user is filling any liquid in the pipette and also prevent plunger's inward movement due to the force exerted by the atmospheric pressure due to presence of partial vacuum created inside the barrel, when the plunger is pulled out by the user to fill a liquid in the pipette, thereby achieve accuracy in filling the pipette.

Yet another aspect of the present invention, wherein the elastomeric members are rubber band (9, 10).

Still another aspect of the present invention relates to a pipette arrangement comprising a pipette (P) connected with at least one semi-automatic pipette filler (SAPF) instrument, wherein the semi-automatic pipette filler instrument comprising at least one assembly of plunger (1) and suction chamber or barrel (2), wherein the assembly comprising a plunger (1) and reciprocate inside the barrel (2), the barrel having an inlet port (2i) and outlet port (2o) and at least one aperture ( 3) on the body, a threaded spacer (4) is being configured inside the barrel (2) along the plunger (1), the threaded spacer (4) is being adapted and accommodated in the space available in the plunger (1) so as to reciprocate along the plunger (1), the threaded spacer is being provided with means (5, 6) to adjust the displacement of the threaded spacer (4) and plunger (1) inside the barrel (2), a pair of safety means (7, 8) are provided with elastic members (12,13) at the outlet port (2o) of the barrel (2) that are being in contact with the plunger (1), at least one connector (14) to connect the pipette (P) and the pipette filler instrument (SAPF).

One another aspect of the present invention, wherein pipette (P) is connected either permanently or temporarily with pipette filler instrument. Yet another aspect of the present invention, wherein pipette (P) is connected permanently with pipette filler instrument (SAPF) by fusing the outlet port (PO) of pipette (P) and inlet (SAPFi) of pipette filler instrument.

Yet another aspect of the present invention, wherein pipette (P) is connected temporarily with pipette filler instrument by a connector (14).

Yet another aspect of the present invention, wherein the connector (14) is selected from two way connector (20) or three way connector (21) or four way connector (22).

Yet another aspect of the present invention, wherein the pipette is connected temporarily with pipette filler instrument by a connector (14) having first opening (14a) in accordance with outlet port (PO) of pipette (P) and second/ third /fourth openings (14b or 14c or 14d ) in accordance with inlet port (SAPFi) of pipette filler instruments.

Yet another aspect of the present invention, wherein the connector (14) for is a conduit of glass or elastomeric material.

Yet another aspect of the present invention, wherein the connector (14) is preferably a conduit of elastomeric material.

A further aspect of the present invention, wherein the connector (14) is preferably a two way connector (14a, 14b) of elastomeric material that is having a proximal end (14a) being connected with outlet port (PO) of pipette (P) and distal end (14b) is connected to inlet port (SAPFi) of pipette filler instrument (SAPF), so as to form essentially an air tight joints.

Yet another aspect of the present invention, wherein the connector (14) is encased with a second conduit (15) of having higher rigidity and stiffness to prevent the connector from twisting, wagging, pinching or bending during handling pipette and pipette filler instrument.

Yet another aspect of the present invention, wherein the second conduit (15) is made of PVC material and serrated from outside surface. Yet another aspect of the present invention, wherein the second conduit (15) is slidably adjusted on the connector (14) while assembling or disassembling the pipette and pipette filler instrument.

Yet another aspect of the present invention, wherein the said arrangement consisting at least one supporting member (16) being provided outside the pipette (P) and the pipette filler instrument (SAPF) to keep the arrangement / assembly firmly.

Yet another aspect of the present invention, wherein the supporting member (16) is a steel rod (17) or cable tie, being attached outside the glass pipette (P) and the pipette filler instrument (SAPF).

Yet another aspect of the present invention, wherein the steel rod (17) is provided in such a manner that the one end (17b) of steel rod (17) is being passed through the outlet port (2o) of the barrel (2) and bent and other end (17p) of steel rod (17) is held with ring type metal clamp (18) fasted with pipette outside to the ensure the pipette and the pipette filler instrument prevent dismantling during user.

Yet another aspect of the present invention, wherein the steel rod (17) is kept along with the assembly of plunger and barrel with the help of metal clasp (19 ) and rubber band (10).

Yet another aspect of the present invention, wherein the metal clasp (19) and rubber band (10) wound in such a manner that enables quick and easy dismantling of pipette with assembly of plunger and barrel.

Yet another aspect of the present invention, wherein the metal clasp (19) is a Ω- shaped and rubber band is placed inside the a Ω-shaped clasp and the rubber band (10 is wound around the barrel and after desired turns, placed again in the Ω-shaped metal clasp.

Yet another aspect of the present invention, wherein to unwind the metal clasp (19), freeing one end of the rubber band from the metal clasp, unwinds the rubber band. A further aspect of the present invention relates to pipette arrangement for a person on wheel chair or of short height comprising a pipette (P) connected with at least two semi-automatic pipette filler (SAPF) (PFl and PF2) instrument, whereby each pipette filler instrument (PFl & PF2) having at least one assembly of plunger (1) and suction chamber or barrel (2), wherein the assembly comprising a plunger (1) and reciprocate inside the barrel (2), the barrel having an inlet port (2i) and outlet port (2o) and at least one aperture ( 3) on the body, a threaded spacer (4) is being configured inside the barrel (2) along the plunger (1), the threaded spacer (4) is being adapted and accommodated in the space available in the plunger (1) so as to reciprocate along the plunger (1), the threaded spacer is being provided with means (5, 6) to adjust the displacement of the threaded spacer (4) and plunger (1) inside the barrel (2), a pair of safety means (7, 8) are provided with elastic members (9,10) at the outlet port (2o) of the barrel (2) that are being in contact with the plunger (1), at least one connector (14) with three way (14a, 14b, 14c) to connect the pipette (P) and the two assembly (PFl & PF2), that are at positioned at 90° to each other, and at least one supporting member (16) being provided outside the pipette and the assembly of plunger and barrel to keep the pipette filler instrument firmly with pipette.

Yet another aspect of the present invention, wherein in the first assembly of plunger & barrel (PFl), the plunger is capable to move vertically and in the second assembly the plunger (PF2) is capable to move horizontally.

Yet another aspect of the present invention, wherein the first (PFl) and second (PF2) assembly of plunger & barrel are having either of same capacity or variable capacity.

Yet another aspect of the present invention, wherein the first (PFl) and second assembly (PF2) of plunger & barrel is in the range of 1ml to 50ml.

Yet another aspect of the present invention, wherein the person on wheel chair or of short height operate the second plunger and barrel assembly (PF2) that is horizontal to the first assembly (PFl).

Yet another aspect of the present invention, wherein the pipette arrangement having lower risk of occurrence of repetitive stress injuries during operation. A still further another aspect of the present invention relates to a modified pipette (MP) comprising an inlet port (100) and outlet port (200), whereby the outlet port (200) is a suction chamber or barrel, wherein a plunger (201) with or without grooves reciprocate inside the chamber or barrel (200), the barrel having at least one aperture (202) on the body, a threaded spacer (203) is being configured inside the barrel (200) along the plunger (201), the threaded spacer (203) is being adapted and accommodated in the space available in the plunger (201) so as to reciprocate along the plunger, the threaded spacer (203) is being provided with means (204, 205) to adjust the displacement of the threaded spacer and plunger inside the barrel, a pair of safety means (206, 207) are provided with elastic members (208, 209) on the barrel (200) that are being in contact with the plunger (201).

A still another aspect of the present invention relates to a kit of pipette filing instrument, the kit comprising a) at least one assembly of plunger and barrel (500), wherein the barrel is having inlet port, outlet port, an aperture near to inlet port and two aperture 180° near to outlet port, b) at least one threaded spacer (501) along with big nut (502) and small nut (503), c) at least a pair of safety screws (504, 505), d) at least two pair elastic members (506, 507), e) at least one connector (508) with two way opening or three way opening, f) at least one supporting member (509) in the form of steel rod or cable, g) second serrated connector (510) for encasing the first connector, h) Ω-shaped clasp (511), i) Bunch of Rubber bands (512), and j) One or more ring type metal clamp (513),

A further another aspect of the present invention relates to a method of operating the pipette filler instrument, the method comprising the steps of

(i) connecting the pipette (P) and pipette filing instrument (SAPF) with airtight sealing,

(ii) keeping the first end (PI) of pipette inside the container (C) filled with solution,

(iii) pulling the plunger (201) of pipette while placing finger on the aperture (202) of the barrel (200), so as so create vacuum in the barrel and solution climb up in the pipette up to a predefined height in the pipette, as per the adjustment of big nut (204) and small nut (205) on the threaded screw (203) in the barrel (200), and (iv)releasing the solution filled in the pipette (P) by Mode (1) by pushing the plunger in; or Mode (2) by removing the syringe by twisting; or Mode (3): by pushing the plunger up to certain point and then removing the syringe by slight twisting; or Mode (4): by lifting the finger covering the pin hole on the barrel; or Mode (5): by pushing the plunger up to certain point and then lifting the finger covering the pin hole on the barrel.

DESIGN DETAILS OF THE PIPETTE FILLER INSTRUMENT WITH ITS DEVELOPMENT DESIGNS

(1) The pipette filler is prepared from a 20ml disposable medical grade polypropylene syringe with Luer slip tip shown in figure 2.

(2) The pipette filler is also prepared from a 20ml disposable medical grade polypropylene syringe with Luer slip tip shown in figure 2.

(3) Both syringes have the same Luer slip tip dimension.

(4) Here the syringe is a system consisting of a barrel and a plunger mounted with a gasket (rubber bung) mounted on the top end of the plunger

(5) Before using the syringe, it is tested for its leak-proof quality by blocking the Luer tip on the barrel with a finger, pulling out the plunger and then checking the recoil of the plunger when released.

(6) The details described below involves syringes

(7) Next, the stem of a 20ml glass cylindrical pipette is inserted into an inch long rubber tubing of 6mm diameter. It is done carefully to avoid breaking the stem of the glass pipette.

(8) Into the other end of the same rubber tubing is inserted a female Luer slip stub without the needle as shown in figure 3.

(9) Next, the Luer slip tip of the syringe is inserted into the female Luer stub lodged inside the rubber tubing.

(10) This assembly involving a 20 ml glass pipette, a 20 ml syringe, rubber tubing and a female Luer stub, shown in figure 4a will be referred to as proposed invention (SG-IM design I). For comparison, the imported manual rubber pipette filler from D&N is shown in fig 4b. (11) To check the performance of design I (figure 4a), the assembly is held as shown in figure 5a. First the plunger is completely pushed inside the syringe. Next the business end of the glass pipette is dip into a beaker containing water. Water is sucked up into the pipette by pulling the plunger and is held by fingers as shown in figure 5b to prevent its slow recoil. Dispensing of water from the pipette is attempted by three distinct modes. Mode 1 : By just pushing the plunger in; Mode 2: By removing the syringe from the female Luer stub by slight twisting as shown in figure 6; Mode 3: By pushing the plunger up to certain point and then removing the syringe from the female Luer stub by slight twisting;

(12) As an proposed modification to design I (figure 4a), a pin hole is drilled into the barrel at a 2 ml mark. Purpose: The reason is to check whether or not water can be dispensed from the pipette up to the calibrated mark using one hand only by mode 4: by just lifting the finger covering the pin hole on the barrel; Mode 5: By pushing the plunger up to certain point and then lifting the finger covering the pin hole on the barrel.

(13) The modified pipette filler shown in figure 7 will be referred to as design II.

(14) To check the performance of design II (figure 7), the assembly is held as shown in figure 8 with the middle finger covering the pin-hole. First the plunger is completely pushed inside. Next the business end of the glass pipette is dipped into a beaker containing water which is sucked up into the pipette by pulling the plunger gradually and keeping the pinhole closed with the finger during the filling process. Plunger is always held by fingers to prevent the small recoil due to suction created in the syringe. Dispensing of water from the pipette is attempted by 5 distinct modes. Mode 1 : By just pushing the plunger in; Mode 2: By removing the syringe from the female Luer slip stub by slight twisting as shown in figure 6; Mode 3 : By pushing the plunger up to certain point and then removing the syringe from the female Luer slip stub by slight twisting; Mode 4: by just lifting the finger covering the pin hole on the barrel; Mode 5: By pushing the plunger up to certain point and then lifting the finger covering the pin hole on the barrel.

(15) As an ingenious modification to the previous designs, a pair of rubber bands is used to fasten the plunger to the ears of the barrel as shown in figure 9. Purpose: To check whether or not instead of holding the plunger with finger, can the rubber bands wound on the barrel and the plunger prevent the plunger from small recoil (sliding in motion) due to pressure difference existing between the inside and outside of the syringe due to suction created in the syringe after pulling the plunger.

(16) The pipette filler shown in figure 9 will be referred to as design III. To check its performance it is held as shown in figure 10.

(17) In another proposed modification to the design III (figure 9), two holes are drilled towards the end of the barrel to hold a pair of screws as shown in figure 11. Purpose: The reason is to check whether or not the pair of screws would work as a stopper to prevent detachment of the plunger from the barrel which would result in loss of suction during pipette filling.

(18) Rubber sleeves as shown in figure 11 are mounted loosely on the pair of screws mentioned in the previous step. Purpose: The reason is to check the following: (i) whether or not the rubber sleeves alone or along with the rubber bands can prevent the recoil of the plunger due to suction created, (ii) whether or not the rubber sleeves can prevent the plunger from being scratched by the tapered end of the screws.

(19) The rubber sleeves are cut from the same rubber tube (6mm diameter) used for the neck.

(20) The modified pipette filler shown in figure 11 will be referred to as design IV

(21) In another modification to the design IV (figure 11), a screw- along with a nut is inserted between the barrel and the plunger as shown in figure 12. Purpose: The reason is to check whether or not the screw along with the nut as an adjustable spacer in 20 ml syringe could prevent the liquid from entering/overflowing into the syringe while using pipettes of 5, 10 and 20 ml capacity. Some liquids can damage the syringe as well as the rubber tubing.

(22) The adjustable spacer is prepared by sawing off the head of the 9.5 cm long screw to enable inserting between the barrel and the plunger. The metal disc (figure 12) has been attached to one of the ears of the barrel with a screw. It can also be attached using a 19 mm metal binder clip shown in figure 27. The purpose of the metal disc is to prevent the nut of the adjustable spacer from slipping inside the barrel when the plunger is pushed inside.

(23) The modified pipette filler shown in figure 12 will be referred to as design V (24) In another ingenious modification to the design V (figure 12), the soft rubber neck of the assembly is snugly encased in a PVC tube (7.5 cms long and 12 mm diameter) as shown in figure 13. Purpose: The reason is to check whether or not the PVC tube can shield the rubber neck from inadvertent pinching, twisting, wagging or bending of the soft rubber neck during handling which can cause the liquid in the pipette to eject and cause error.

(25) The PVC tube is first slipped over the stem of the pipette as shown in figure 14. Then the stem is carefully inserted into one end of an inch long rubber tubing (neck) with 6mm diameter as shown in figure 14 resulting in an airtight fitting. The other end of the rubber tubing or the neck is inserted into another rubber tube ~0.5cm long (figure 14) with its outer diameter matching the inner diameter of the PVC tube.

(26) Then the female Luer stub as shown in figure 15 is embedded completely into the opening of the rubber tubing. Now the PVC tube is carefully slid sideways until it covered the whole length of the neck as shown in figure 13. At the other end of the PVC tube, rubber pieces are inserted between the stem and the PVC tube to make it sturdy as shown in figure 13. The PVC tube with grooves as shown in figures 13-14 is available in most hardware shops as tube joint.

(27) Next, the Luer slip tip of the syringe is inserted in the female Luer stub embedded in the rubber tubing as shown in figure 15.

(28) The modified pipette filler shown in figure 16 will be referred to as design VI

(29) To check the performance of design VI (figure 16), the assembly is held as shown in figure 17. Water is drawn into the pipette by pulling the plunger until it came to a halt against the screws. Dispensing of water from the pipette is attempted by 5 modes. Mode 1 : By just pushing the plunger in; Mode 2: By removing the syringe from the female Luer slip stub by slight twisting as shown in figure 18; Mode 3: By pushing the plunger up to certain point and then removing the syringe from the female Luer slip stub by slight twisting; Mode 4: by just removing the finger covering the pin hole on the barrel; Mode 5: By pushing the plunger up to certain point and then removing the finger covering the pin hole on the barrel. (30) In another proposed modification to the design VI (figure 16), ring type metal clamps fastened to the stem of the pipette and to the barrel as shown in figures 19-20. Purpose: The reason behind this step is to check whether or not a cable tie can be used to securely clasp the syringe to the glass pipette via the metal clamps. This need is felt because there is always a possibility in the previous designs of the syringe easily being separated/ detached from the pipette on application of little force during handling resulting in (i) pipette falling down and suffering damage (ii) loss of suction and incomplete filling of the pipette amounting to loss of time and effort.

(31) The modified pipette filler shown in figure 21 will be referred to as design VII

(32) The extra length of the cable tie, as in the case of a waist belt, is inserted in a metal buckle as shown in figure 21.

(33) In another ingenious modification to the design VII (figure 21), a pin hole is drilled into the barrel at 12 ml mark. Purpose: In design VII (figure 21), water cannot be dispensed by syringe removal (mode II) as it is securely fastened to the pipette by cable tie. So the reason is to check whether or not when the finger is lifted from the pin hole, can water be dispensed from the pipette up to the calibrated mark without pushing the plunger.

(34) The modified pipette filler shown in figure 22 will be referred to as design VIII

(35) To check the performance of design VIII (figure 22), the assembly is held as shown in figure 23 with the thumb covering the pin-hole. First the plunger is completely pushed inside. Next the business end of the glass pipette is dipped into a beaker containing water which is sucked up into the pipette by pulling the plunger gradually and keeping the pinhole closed with the thumb during the filling process. For dispensing water from the pipette the thumb is lifted from the pin-hole.

(36) As an alternative to design VIII (figure 22), where all the features have been retained except, instead of a cable tie, a thin metal rod, is used to securely fasten the syringe to the pipette as shown in figure 24. The thin steel rod is available in most cycle spare parts shops.

(37) The modified pipette filler shown in figure 24 will be referred to as design IX. (38) The performance of the pipette fillers of designs I-IX are evaluated for other volumetric pipettes: 5, 10 and 50 ml

(39) The performance of the pipette fillers of designs I-IX are evaluated for graduated pipettes. One such assembly for a 10 ml graduated pipette using a 10 ml syringe is shown in figure 28. Various components used in assembling such a device is shown in figure 29

(40) As a modification to design II (figure 7), the rubber tubing connecting the syringe to the stem of the pipette is replaced with the rubber neck grafted from a defective commercial 2 valve manual rubber pipette filler (figure 1). Purpose: The reason is to check whether or not some of the commercial rubber pipette fillers which become dysfunctional for reasons mentioned on page 2 can be put to good use by using their neck as a 3-way adaptor.

(41) The modified pipette filler shown in figure 31 will be referred to as SG-IM pipette filler design XI. On one port of the 3-way adaptor is attached the stem of the pipette. On another port is attached a 20 ml syringe via a female Luer slip stub. On the third port is attached a 2ml syringe via a female Luer slip stub. Purpose: The reason is to check (i) whether or not by moving the plunger of the smaller 2 ml syringe, fine adjustment of the water level could be achieved, (ii) position of the two syringes could be swapped (figures 32 & 33) without affecting the performance which could suit some users.

(42) To ensure air-tight fitting, rubber bands are wound around both the syringe docking ports in a conventional manner. For the port where the stem of the pipette is docked, the rubber band cannot be wound around in a conventional manner and therefore is wound around in a novel manner using a metal clasp as shown in figure 31. Teflon tape is also used in all the three ports of the 3- way adaptor to ensure airtight fit.

(43) To check the performance of design XI (figure 31), the assembly is held as shown in figures 32 & 33. The other hand is used to pull the plunger of 20 ml syringe to draw water into the pipette. The plunger of the smaller 2 ml syringe is used to attempt fine adjustment of the water level in the pipette. Dispensing of water from the pipette is attempted my mode 2 (removal of syringe) and mode 4 (lifting of finger from the pinhole).

(44) The performance of design XI in both vertical and horizontal positions is also checked by replacing 2ml syringe with 1ml syringe as shown in figures 34 & 35. Purpose: The reason behind attaching 20 mL syringe in port 2 (figures 33 & 35) is to check whether or not it will be convenient for wheelchair bound users to operate pipette filler in horizontal position.

(45) As a modification to design XI (figures 31, 32 & 34), a threaded rod along with a nut constituting the adjustable spacer is placed between the plunger and the barrel as shown in figure 36. Purpose: The reason is to check whether or not the adjustable spacer could prevent overfilling of the pipette.

(46) As a modification to design XI (figures 31 , 32 & 34), two screws orthogonal (-90 degrees) to each other with rubber sleeves are fixed to the barrel as shown in figure 38. Purpose: The reason is to check whether or not the pair of screws can: (i) prevent the plunger from being detached from the barrel during pulling, (ii) keep the adjustable spacer in the right alignment with respect to the barrel.

(47) As a modification to design XI (figures 34 & 35), a pinhole is made on the barrel of the 1-ml syringe at 0.7ml mark as shown in figure 36. Purpose: The reason is to check whether or not by gently pulling the plunger beyond the pin hole, the pipette could be emptied up to the calibrated level.

(48) As a modification to design XI (figures 31 , 32 & 34), a thin metal rod is inserted from the hole of the metal disc placed on the ear/grip of the barrel and slipped through the ring type metal clamp and rubber sleeves on the pipette stem as shown in figure 36. A rubber band is tightly wound in a unique manner around the barrel and the metal rod using a Ω-shaped metal clasp as shown in figure 36. Purpose: The reason behind using the metal rod is to check whether or not the metal rod (i) can hold both the glass pipette and the pipette filler firmly together, (ii) can prevent the 3 -way rubber tubing from twisting, bending and flexing.

(49) The modified design incorporating adjustable metal spacer, fixed screws, pinhole on 1 ml syringe, metal rod and Ω-shaped metal clasp for rubber band will be referred as SG-IM semi-automatic pipette filler (SAPF) design XII shown in figure 36.

(50) To check the performance of SG-IM SAPF design XII, the assembly is held as shown in figure 37. To fill water in the pipette, the nut is positioned accordingly on the threaded metal rod placed between the barrel and the plunger as shown in figure 37. Next, the plunger of the 20 ml syringe in port 1 is pulled until it came to a halt against the fixed screws. To empty water from the pipette, the plunger of the 1 -mL syringe in port 2 is pulled beyond the pinhole.

(51) Besides testing with water, experiments are also performed using 0.05N permanganate solution, 0.05N KOH solution, ethanol and acetone at room temperature.

(52) The pipettes prior to being used for the experiments are washed with mild detergent solution, rinsed with water and finally rinsed with acetone to remove traces of water in the pipettes. This is performed using the pipette filler as described above. The plunger is repeatedly pushed in & out of the syringe to expel the residual acetone until the pipette is dry.

Results and Discussion

(1) In all the designs of the pipette filler tested, the syringe is connected to the pipette by an inch long rubber tubing of 6mm diameter because neither the Luer slip tip of the syringe nor the female Luer stub (figure 2) mounted on the syringe tip directly fits into the stem of the pipettes used. The glass pipette and the female Luer stub inserted into both ends of the rubber tubing are air-tight.

(2) The pipette filler of design I (figure 4a) involving a 20 ml disposable plastic syringe exhibited good suction ability and successfully accomplished the task of filling a 20 ml volumetric pipette with water up to the desired mark. The rubber tubing is airtight at both the ends. A fine control over dispensing of water from the pipette by pushing the plunger is witnessed. Water exited the pipette as long as the plunger is pressed /pushed. As soon as the plunger is stopped, water too ceased to flow. It is possible to dispense water from the pipette drop-by-drop or as a continuous jet depending on the manner in which the plunger is pressed/ pushed. It is possible to retract a hanging water drop by slightly pulling the plunger. However in this design I, the plunger needed to be held after being pulled as shown in figure 4a to stop the recoil or the small inward movement of the plunger invisible to the eye due to pressure difference arising from the suction created by pulling of the plunger. This small inward movement/ recoil of the plunger invisible to the eye if not stopped results in unwanted dripping of the water from the pipette, which initially gave a false impression of air leak somewhere in the assembly. When the plunger is somehow held, dripping of water from the pipette is not observed. Various modes of dispensing 20ml water from the pipette are investigated.

(3) In mode 1, where the plunger is pushed to eject water, the user has to carefully control the movement of the plunger to eject water up to the calibrated level (desired effect) otherwise there is a good chance that water will be completely expelled from the pipette and result in error. The advantage of this mode is that the user has control over the rate of dispensing of water which depends upon the manner in which the plunger is pushed/ pressed.

(4) In mode 2, where the syringe is removed after the pipette has been filled up to the desired level, water exits the pipette up to the calibrated level (desired effect) without the need to push the plunger. The advantage of mode II over mode I of dispensing is that it spares the user the extra effort needed to push the plunger and manually adjust the water level at the calibrated point of the pipette. However, in mode II the user has no control over the rate of dispensing of water as the process occurs under ambient atmospheric pressure.

(5) In mode 3, which is basically a combination of modes 1 & 2 of dispensing, where the plunger is first pushed/ pressed up to a certain point and then the syringe is removed, water is ejected from the pipette up to the calibrated level (desired effect) without the need for the user to interfere. The user can to a certain extent control the rate of dispensing of water during pushing/pressing of the plunger.

(6) Dispensing by mode 2 or mode 3 from a calibrated pipette is accurate because when a pipette manufacturer calibrates the pipette, the calibration is carried out under ambient atmospheric pressure. That means after dispensing of specified volume of liquid under ambient atmospheric pressure, there will still be a small amount of liquid left behind in the pipette near its tip apparently due to capillary forces balancing the downward force exerted by the ambient atmospheric pressure. In this way, the specified volume (in this case, 20 ml) will be dispensed, and the remaining liquid should not be expelled as it will cause error in cases where accurate dispensing of specified volume of liquid is required.

(7) All the three modes of dispensing water from the pipette require both the hands. From pipette ergonomics, it is clear that mode 2 of dispensing of water mitigates the risks of occurrence of repetitive stress injuries (RSI) as pushing of plunger is now obviated.

(8) From the results it is clear that the pipette filler of design I can dispense 20 ml of water from the 20 ml pipette accurately, precisely, quickly and with lower risk of occurrence of repetitive stress injuries (RSI) compared to commercial pipette filler (figure 4b). In design I two hands are required to dispense water from the pipette.

(9) The performance of pipette filler of design II (figure 7) is indeed very satisfactory as the pin hole successfully served its purpose stated in para 12 of the design section. The pinhole feature makes the SG-IM pipette filler very distinct from any commercially available pipette filler. There is no need to remove the syringe as done in design I (figure 6) for dispensing purpose. It is possible to accurately dispense 20 ml water from the pipette up to the calibrated mark by just lifting the finger from the pin hole or just loosening the finger on the pin-hole. Once the pipette has been filled, the finger-pinhole combination allowed water level to be adjusted up to the desired mark without the need to push the plunger. The dispensing process could be carried out by just one hand in comparison to design I. This whole exercise involved only pulling of the plunger to fill the pipette and the rest (water level adjustment and final dispensing) is managed through the pin hole. This further mitigated the risks of occurrence of repetitive stress injuries (RSI) as pushing of plunger is now completely obviated. The pin hole allowed dispensing of water from the pipette by just one hand compared to design I where both the hands are required to dispense water by any of the three modes.

(10) From the results it is clear that the pipette filler of design II (figure 7) can dispense 20 ml of water from the 20 ml pipette accurately, precisely, quickly and with lower risk of occurrence of repetitive stress injuries (RSI) compared to commercial pipette filler (figure 1). The presence of pin hole allowed dispensing of water from the pipette by just one hand.

(11) The performance of pipette filler of design III (figure 9) is indeed very satisfactory as the pair of rubber bands successfully served their purpose stated in para 15 of the design section. The rubber bands wound around the ear of the barrel and the plunger acted as a harness which held the plunger and prevented it from small recoiling or sliding in motion due to pressure difference arising from the suction created by pulling of the plunger. This small recoil or inward movement of the plunger invisible to the eye if not stopped results in unwanted dripping of the water from the pipette, which initially gave a false impression of air leak somewhere in the assembly. The rubber bands did not interfere with the pushing of plunger. The fact that fingers are no longer required for holding the plunger mitigated the risks of occurrence of repetitive stress injuries (RSI) to the fingers. It is possible to dispense water from the pipette by all the 5 modes.

(12) From the results it is clear that the pipette filler of design III (figure 9) can dispense 20 ml of water from the 20 ml pipette accurately, precisely, quickly and with lower risk of occurrence of repetitive stress injuries (RSI) compared to commercial pipette filler (figure 1). The performance of design III (figure 9) is better than design I (figure 4a) as no dripping of water is observed. The pair of rubber bands wound around the plunger and the syringe proved to be adequate in preventing the small recoil/ sliding in motion of the plunger responsible for unwanted dripping normally seen in design I (figure 5a).

(13) The performance of pipette filler of design IV (figure 11) is indeed very satisfactory as the pair of screws successfully served their purpose stated in para 17 of the design section. The screws prevented the plunger from being inadvertently detached from the barrel.

(14) The rubber sleeves in design IV (figure 11) successfully served the purposes stated in para 18 of the design section.

(15) From the results it is clear that the pipette filler of design IV (figure 11) can dispense 20 ml of water from the 20 ml pipette accurately, precisely, quickly and with lower risk of occurrence of repetitive stress injuries (RSI) compared to commercial pipette filler (figure 1).

(16) The performance of pipette filler of design V (figure 12) is indeed very satisfactory as the screw-nut system successfully served its purpose stated in para 21 of the design section. By proper adjustment of the adjustable spacer, the same 20 ml syringe based pipette filer can safely fill 5, 10 and 20 ml pipettes with eyes shut without any possibility of overfilling of the pipette irrespective of how the plunger is pulled. On the other hand, if one is not careful and watchful, liquid being sucked up into the pipette by a commercially available pipette filler (figure 1) can easily overfill the pipette and move into the pipette filler and cause damage.

(17) From the results it is clear that the pipette filler of design V (figure 12) can dispense 20 ml of water from the 20 ml pipette accurately, quickly, with lower risk of occurrence of repetitive stress injuries (RSI) compared to commercial pipette filler (figure 1). The combination of adjustable spacer and pinhole features make the SG-IM pipette filler truly semi-automatic in performance.

(18) The performance of pipette filler of design VI (figure 16) is indeed very satisfactory as the PVC tube successfully served its purpose stated in para 24 of the design section. In the previous designs there is always a great risk of water leaking out of the pipette due to inadvertent pinching, twisting and bending/flexing of the rubber tubing. Considerable care is taken while handling previous designs. By shielding/insulating the flexible rubber tubing (neck) with the hard PVC tube, the inadvertent pinching, twisting, bending/flexing of the rubber tubing is completely ruled out. It is analogous to bone-marrow. Here the soft flexible rubber tube or the neck is the marrow and the hard PVC tube acts as the bone. When the rubber tube is inside a hard PVC tube, the above risks are mitigated to a considerable extent and the syringe stays upright.

(19) The PVC tube also serves the important purpose of concealing the non- obvious vital component: the 2- way rubber connector from imitation.

(20) From the results it is clear that the pipette filler of design VI (figure 16), as distinct from commercial pipette filler (figure 1), can dispense 20 ml of water from the 20 ml pipette accurately, precisely, quickly, with lower risk of occurrence of repetitive stress injuries (RSI). In fact, design VI (figure 16) is more robust than the commercially available pipette filler (figure 1) as rubber neck of latter is susceptible to pinching, twisting and bending/flexing. The combination of adjustable spacer and pinhole features make the SG-IM pipette filler design VI truly semi-automatic in performance.

(21) The performance of pipette filler of design VII (figure 21) is indeed very satisfactory as the cable tie successfully served its purpose stated in para 30 of the design section. The cable tie clasped both the syringe and the glass pipette tightly together with no chance of them separating/ detaching from each other during pulling of the plunger. The cable tie achieved the objective because of the hard PVC tube. This unique feature distinguishes design VII (figure 21) from the previous designs where there is always a risk of syringe separating/ detaching from the glass pipette if mishandled. Since the syringe is now securely clasped to the pipette, dispensing of water from the pipette in the absence of a pin hole can only occur by mode 1 (by pushing the plunger).

The advantage of design VII (figure 21) over all earlier designs lay in the fact that due to the cable tie the syringe could not be separated/ detached from the pipette even if the plunger is pulled hard. The risk of glass pipette slipping out of the assembly is very less even when compared to the commercially available pipette filler (figure 1) where there is no such clasp to hold the pipette filler and the glass pipette firmly. The loop formed by the cable tie in design VII (figure 21) allows the assembly to be securely hung vertically from a wall fixture.

The design VII (figure 21) enables easy removal of the syringe from the assembly by just dislodging one of the strings from the ring-type metal clamps. In this manner there is no need to either cut or pry open the cable tie with a small screw driver. The combination of adjustable spacer and pinhole features make the SG-IM pipette filler design VII truly semi-automatic in performance.

(22) The performance of pipette filler of design VIII (figure 22) is indeed very satisfactory as the pin hole successfully served its purpose stated in para 33 of the design section. The syringe and the glass pipette are securely clasped and it is also possible to dispense water by single hand (mode 4) and both the hands (mode 5)

(23) From the results it is clear that the pipette filler of design VIII (figure 22), as distinct from commercial pipette filler (figure 1), can dispense 20 ml of water from the 20 ml pipette accurately, precisely, quickly, safely and with lower risk of occurrence of repetitive stress injuries (RSI) [4]. The combination of adjustable spacer and pinhole features make the SG-IM pipette filler design VIII truly semi-automatic in performance.

(24) The performance of pipette filler of design IX (figure 24) is indeed very satisfactory as the steel rod successfully replaced the cable tie as stated in para 36 of the design section. It strongly holds the glass pipette and the syringe together and also keeps the latter stand upright and not canted as distinct from the cable tie (figure 25). Besides, cheap and widely available steel rod allows use of only one ring type metal clamp instead of two in design VIII (figure 23) contributing towards making pipette filler light weight and less expensive (each ring type metal clamp costs rupees ten). The steel rod holding both the syringe and the pipette tightly can be easily removed by first loosening the screw on the metal clamp on the stem of the pipette and then pulling out the rod.

(25) From the results it is clear that the pipette filler of design IX (figure 24), as distinct from commercial pipette filler (figure 1), can dispense 20 ml of water from the 20 ml pipette accurately, precisely, quickly, safely, and with lower risk of occurrence of repetitive stress injuries (RSI). Water can be dispensed by single hand (mode 4) and both the hands (mode 5). The combination of adjustable spacer and pinhole features make the SG-IM pipette filler design IX truly semi-automatic in performance.

(26) Besides water, the proposed pipette fillers of designs I-IX could successfully fill and dispense other liquids like 0.05N permanganate solution, 0.05N KOH solution, ethanol and acetone at room temperature. No unwanted dripping is observed as long as the plunger is held either by hand or other means described above.

(27) Unlike commercial pipette fillers, the proposed pipette filler of any design (I-IX) can accomplish both the task of filling pipettes and also cleaning them by strong air jet generated by pushing the plunger. Since water or any liquid can be completely expelled from the pipette due to high pressure generated by pushing in the plunger, all the designs of the pipette filler enabled cleansing of the pipette with appropriate liquid. This feature makes these designs quite distinct from the commercially available pipette filler (figure 1).

(28) It is observed that pipette fillers made from syringes marked 5, 10, 20 and 50 ml could precisely and accurately dispense liquids from the pipettes of capacities 5, 10, 20 and 50 ml respectively. It is possible to retract a hanging water drop by pulling the plunger. It is also observed that the size mismatch between syringe and pipette did not affect the performance as long as the capacity of the syringe used is larger than that of the pipette attached. (29) For graduated pipettes of various sizes, it is observed that the desired volume of liquid could be accurately and precisely dispensed using a 5/10/20/50 ml syringe based pipette filler. No dripping of liquid is observed. This implied good suction ability of the pipette fillers and air-tight fittings at both ends of the rubber tubing. It is possible to dispense any liquid either as a continuous stream or drop-by-drop. This depended on how the plunger is pushed. Pipette fillers based on 10 ml syringes (figure 28) performed satisfactorily for dispensing liquids from 10ml graduated pipettes.

(30) A 50 ml syringe is used as universal pipette filler as shown in figure 27. All the 20ml syringe based designs (I-IX) is successfully implemented on a 50 ml syringe. A 50ml syringe based pipette filler can be successfully used for filling and accurately dispensing liquid from any graduated or volumetric pipette ranging from 5-50 ml. Liquid exited the pipette as long as the plunger is pressed /pushed. As soon as the plunger is stopped, liquid too ceased to exit. It is possible to dispense liquid from the pipette drop-by-drop or as a continuous jet depending on the manner in which the plunger is pressed/ pushed.

As in the case of 20 ml syringe based pipette fillers discussed earlier, fine control over dispensing of liquid from the pipette is also observed for 50ml syringe based pipette fillers by various modes: mode 1 (pushing the plunger), mode 2 (removing the syringe), mode 3 (mode 1 followed by mode 2), mode 4 (lifting the finger on the pin hole) and mode 5 (mode 1 followed by mode 4). The combination of adjustable spacer and pinhole features make the SG-IM universal pipette filler truly semi-automatic in performance.

(31) Silicone vacuum grease is applied to ensure smooth movement of the plunger inside the barrel.

(32) The pipette filler designs described above using syringes can also be successfully adopted for syringes of similar design. The designs and performance of pipette filers assembled are similar to those assembled using syringes. Both have same Luer slip tip dimension. This implies that one can replace or substitute the other. Owing to similar features of the syringes from both brands (figure 2), pipette filler designs involving syringes are identical to those involving syringes. However there are some minor differences. For instance, the rubber bands in design III (figure 9) using syringes are wound around the plunger and the ears of the barrel. In the case of design X based on syringes, the rubber bands are wound only on the plunger (figure 26) because the plunger has a V- shaped groove (figure 2) where rubber bands get stuck and prevents the plunger from moving freely if they are wound like in design III (figure 9).

(33) The performance of SG-IM pipette filler of design XI (figure 31) is indeed very satisfactory as the 3-way rubber tubing successfully met the objectives stated in para 40-41 of the design section. It is possible to fill the pipette using the bigger 20 ml syringe and subsequently carry out fine adjustment of the water level in the pipette using the smaller 2 ml syringe. The use of TEFLON tape and rubber bands ensured no unwanted dripping/leaking of water.

(34) The performance of SG-IM pipette filler of design XI (figures 34 & 35) is even better when the 2ml syringe is replaced with 1-ml syringe. The water level in the pipette could be precisely controlled.

(35) Accurate dispensing of water using design XI is achieved either by mode 2 (removal of one of the syringes) or by mode 4 (lifting or loosening of finger from the pinhole). Quick accurate dispensing of water is achieved either by mode 3 (pushing of the bigger plunger followed by removal of the smaller syringe) or by mode 5 (pushing of the bigger plunger followed by lifting or loosening of finger from the pinhole).

(36) The design XI is unique as it allows swapping of the syringe positions as shown in figures 32-35. The performance of the pipette filler is not affected by interchanging the position of the syringes. The other SG-IM pipette filler designs operate in vertical position only.

(37) Handicapped persons who are wheelchair bound and users with shorter heights will find the SG-IM pipette filler of design XI in horizontal position (figures 33 & 35) convenient to operate as the plunger needs to be moved sideways only. In other designs, the plunger needs to be moved vertically which the wheelchair bound users will find it relatively inconvenient as it would involve lifting their body from the wheelchair. This attribute makes the SG-IM pipette filler of design XI more user friendly compared to other designs as it mitigates the risks of occurrence of repetitive stress injuries (RSI) for handicapped persons and users with short height. (38) The successful performance of design XI means that manufacturers of commercial rubber pipette fillers of type shown in figure 1 can now make 3- way adaptors as shown in figure 31-b which will have provisions to attach multiple modified syringes of different capacities as shown in figure 31-b. It is anticipated that this proposed approach will not only mitigate the problems encountered in a commercial pipette filler of type shown in figure 1 but also introduce new capabilities hitherto unreported.

(39) The performance of SG-IM pipette filler of design XII (figures 36-38) is very satisfactory and it met all the objectives listed in para 45-48 of the design section. The thin metal rod: (i) prevented the 3 -way rubber tubing from bending, flexing and twisting, (ii) held both the glass pipette and the pipette filler tightly. It is possible to pull the plunger without any risk of detachment. The adjustable spacer (the threaded rod along with the nut) prevented overfilling of the pipette. The pair of orthogonally fixed screws (figure 38) prevented the plunger from coming out of the barrel and also kept the adjustable spacer aligned with the metal disc. After the pipette is filled by pulling the plunger of the 20mL syringe in port 1 , no dripping of water from the pipette is observed implying apparently no recoil of the plunger due to rubber bands and rubber sleeves mounted on the fixed screws. Of all the syringes (1.0, 2.5, 6.0, 10.0, 20.0, 50.0 mL), it is the l .OmL syringe in which the plunger movement is relatively smooth and requires less effort. Hence, the 1 mL syringe in port 2 enabled fine adjustment of water level in the pipette to the 20 mL graduated mark. Water could be dispensed accurately from the pipette up to the calibrated mark by pulling the plunger of the 1 mL syringe beyond the pinhole. The combination of adjustable spacer and pinhole features make the SG-IM pipette filler design XII truly semi-automatic in performance. Since the plunger movement in 1 mL syringe requires so little effort that its use in design XII mitigates the risk of repetitive stress injury (RSI).

(40) Dismantling of SG-IM SAPF Design XII (figure 36) is quick and easy. This is due to the unique manner in which the rubber band has been wound around the barrel and the rod where two ends of the rubber band is held using a Ω- shaped metal clasp (figure 36). By freeing one end of the rubber band from the metal clasp, unwinds the rubber band. Next, the screw of the ring type metal clamp mounted on the pipette stem (figure 36) is loosened which frees the thin metal rod. With metal rod removed, it is now possible to detach/separate the glass pipette from the pipette filler.

(41) On comparing the SG-IM semi-automatic pipette filler with the imported safety pipette filler (figure 30) the following points emerge. The former is compact and its performance is as good as the latter. So far not a single incident involving liquid moving into the pipette fillers based on design V (figure 12) has been observed. On the other hand, several times the imported safety pipette (figure 4b) filler got filled with liquid because of lack of design V (figure 12) like feature and secondly due to the confusion in pressing of the up (†) or down (j) buttons in the commercial pipette fillers (figure 1).

(42) From the point of view of affordability and availability, the imported pipette filler costs Rs. 400 per piece when purchased in bulk and is available only with select dealers. The syringes used for making the smart pipette filler cost approximately Rs. 5, 10, 15, 25 each for 5, 10, 20 and 50 ml, respectively and are available in any chemist shop. Besides, the syringes being made from polypropylene will last longer than the imported pipette fillers made from natural rubber. If some problem is suspected with the syringe, it can be easily replaced.

(43) In the manuscript syringes of 5, 10, 20 and 50 ml capacity has been used as pipette filler. It is anticipated that syringes of other capacities will work as well.

(44) In the design section it has been mentioned that a pin hole has been drilled on the barrel either at 2ml or 12 ml mark. It is anticipated that the performance of the pipette filler will not be affected if a pin hole is drilled elsewhere on the barrel.

(45) Syringes with Luer slip tip have been used in all the designs described so far.

Syringes with Luer lock tip (threaded tip), can be used in place of slip tip. Purpose: Syringes with Luer lock tip will not easily detach from the female Luer lock stub unlike Luer slip stub (figure 2). (46) Syringes with side nozzles have been used in all the designs described so far. It is anticipated that syringes with nozzles at the centre can be used. Purpose: This will prevent bending of the pipette filler during pushing of the plunger.

ADVANTAGES OF THE PROPOSED INVENTION

The present invention relates to an improved pipette instrument, which is semiautomatic, economical, compact, lightweight, safety pipette filler with ergonomic features designed and assembled from easily available components. Particularly, the semi-automatic pipette filler (SAPF) is capable to operate not only by normal human being but also by handicapped people especially wheelchair bound. The improved pipette instrument is having utility for teaching and research laboratories, small scale industries.

The SG-IM SAPFs can be quickly assembled and dismantled for maintenance, transportation. The SG-IM SAPFs is capable for precise adjustment of water level in the pipette and can be operated in either vertical or horizontal position.

The proposed invention is an inexpensive, rugged, light weight, compact, and user-friendly semi-automatic safety pipette filler with low risks of occurrence of repetitive stress injuries (RSI) compared to commercially available pipette filler has been developed that is performance wise precise and accurate.

Handicapped persons who are wheelchair bound and users with shorter heights will find the pipette fillers convenient to use.

It can perform both the tasks of filling and cleaning the pipette. It can be assembled in a few minutes from disposable polypropylene syringes in addition and other items.

Ingenious modifications carried out on syringes resulted in twelve successful designs of pipette fillers. Some of the novel features like: pin hole, use of rubber bands, adjustable spacer, cable tie, metal rod, 2-way rubber connector and 3-way rubber connector make them quite distinct from the commercial pipette fillers.

Besides, these proposed pipette fillers can dispense liquid from the pipette in five distinct modes. The proposed pipette filler assembled using a 50ml capacity syringe can accurately dispense liquids from 5, 10, 20 and 50 ml volumetric pipettes and graduated pipettes. Any capacity volumetric pipette can be filled with appropriate syringe.

Overall, the proposed pipette filler seems to be a good import substitute in terms of performance and cost.

The pipette fillers of different designs allow five distinct modes of dispensing. Mode 1 : By just pushing the plunger in; Mode 2: By removing the syringe from the female Luer stub by slight twisting; Mode 3 : By pushing the plunger up to certain point and then removing the syringe from the female Luer stub by slight twisting; Mode 4: by just lifting the finger covering the pin hole on the barrel; Mode 5: By pushing the plunger up to certain point and then lifting the finger covering the pin hole on the barrel.

The overall performance of SG-IM SAPFs has been very encouraging. Since pipettes are widely used in large numbers in educational, quality control and research laboratories there is considerable incentive for small scale industries to mass produce SG-IM semi-automatic safety pipette fillers (SAPFs).

The inventors have developed the invention, so that advantage can be achieved in an economical, practical, and facile manner. While preferred aspects and example configurations have been shown and described, it is to be understood that various further modifications and additional configurations will be apparent to those skilled in the art. It is intended that the specific embodiments and configurations herein disclosed are illustrative of the preferred nature of the invention, and should not be interpreted as limitations on the scope of the invention.