AIRUL Azha (Bukit Jalil, Kuala Lumpur, 57000, MY)
MOHD, Rofei (Bukit Jalil, Kuala Lumpur, 57000, MY)
AYMEN, M. Karim (Bukit Jalil, Kuala Lumpur, 57000, MY)
MASURI (Bukit Jalil, Kuala Lumpur, 57000, MY)
WAN ADIL, Wan Jamil (Bukit Jalil, Kuala Lumpur, 57000, MY)
AIRUL Azha (Bukit Jalil, Kuala Lumpur, 57000, MY)
MOHD, Rofei (Bukit Jalil, Kuala Lumpur, 57000, MY)
AYMEN, M. Karim (Bukit Jalil, Kuala Lumpur, 57000, MY)
MASURI (Bukit Jalil, Kuala Lumpur, 57000, MY)
| Claims A sensing system comprising; at least two sensors (10, 20) ; whereby at least one sensor (20) is configured to detect light and one sensor (10) is configured for measuring samples; an analog read-out circuitry connected to at least one sensor (10), at least one adaptive gain control means (40) connected to the light sensor (20) for optimizing the output from the light sensor (20) ; and a differential amplifier (50) ; wherein the adaptive gain control means (40) is configured to optimize the output from both sensors (10, 20) for light compensation, by way of equalizing the light coefficient factor (β, a) by both sensors (10,20) . The sensing system as claimed in Claim 1 wherein at least one sensor (10) is configured to detect ion concentrations in a solution sample and one sensor (20) is configured to detect light (20) . The sensing system as claimed in Claim 1 wherein the differential amplifier (50) comprises two input terminals, one input terminal which is the positive terminal for input from the chemical sensor (10) and the second input terminal which is the negative terminal for input from the light sensor (20) . 4. The sensing system as claimed in Claim output from the differential amplifier (50) is zero light effect signals. 5. A method for use in eliminating light interruption in a sensing system; said method comprising the steps of: providing at least one sensor configured for measuring samples; providing at least one sensor configured for detecting light; directing output from both sensors to a differential circuit; optimizing the output from the sensor for detecting light for light compensation effect; equalizing the light gains from both sensors and producing zero light effect signals. 6. The method as claimed in Claim 5 wherein the step equalizing the light gains from both sensors is performed taking into consideration the light coefficient factors (a, β) for both sensors. |
Field of Invention The present invention relates generally to sensor devices, more particularly to a method for providing enhanced sensing capabilities for integrated wireless ion sensitive field effect transistor (ISFET) sensor devices. Background of the Invention
The integrated ion sensitive field effects technology (ISFET) enables user to effectively sense and thus measure ion concentration in a solution. The recent technological advancement in ISFETS and digital electronics has led to the development of low-voltage, low-power, multifunctional sensor nodes primarily to provide a more unambiguous a sensing output. It is commonly known that for an attempt of sensing ion concentration in solution samples using an ISFET based device, the universal challenges in producing an accurate result based on the sensing are prominently influenced by external factors such as, but not limiting to, temperature, humidity, motion, pressure and the mostly, for the case of ISFETS, is the ambience light. As evident in the accompanyin
light effect for a sensing output is approximately lUUmVpp.
In order to partially resolve this increasingly unsettling drawback, users have started to develop solutions based on filtering out such disruption, for instance incorporating filtering schemes. The light effect may be reduced to about 5% from the original amount of interference as shown in FIG 1 (b) , however it is often overlooked that the imperative damaging factor is the shift in the DC level, which in many cases would lead to the misinterpretation of the measuring solution thus resulting to erroneous ion-concentrations decision .
The number of studies conducted in order to further develop the efficiency and enhance the capability of light filtering has tremendously increased over the past few years. Such studies may become solutions for complications or undesirable characteristics as discussed previously. An exemplary of a proposed solution surfaced was by means of black box enclosure whereby this approach may aid in reducing the light effect however taking into consideration that sensors are typically involved for sensing and cramming these devices into a closure may not be an expeditious solution. This is further unwieldy in the event that the sensing period is extens
for analyzing drifts characteristics.
Whilst many prior art and technology substitutions may be expedient and considerably enhanced in regards to the enhancing ISFETS sensing capabilities, the current condition or challenge of filtering unwanted ambience light disruption to obtain better sensing clarity has yet to be thoroughly resolved. A great majority of devices or methods which may be able to provide at least half of the clarity in sensing and does not disrupt the DC level are more often prohibitively expensive .
As light sources vary, the level of interference varies. It is therefore would be a great advantage is the ISFET device is adapted to be versatile and portable in all conditions of lights thereby providing better sensing capability with reduced light disruption and reduced or zero shifts in direct current (DC) .
Therefore the objective of the present invention is to provide a system and method for providing light disruption immunity for the sensing device, more particularly for ISFET devices, whereby there is provided an adaptive gain control as part of the sensing device. It is yet another object of the present invent
system and method for removing the alternating current (AC) and direct current (DC) components of the light effect. Other objects of this invention will become apparent on the reading of this entire disclosure.
Summary of the Invention In one aspect, the present invention discloses a sensing system comprising; at least two sensors (10, 20) ; whereby at least one sensor (20) is configured to detect light and one sensor (10) is configured for measuring samples; an analog read-out circuitry connected to at least one sensor (10), at least one adaptive gain control means (40) connected to the light sensor (20) for optimizing the output from the light sensor (20) ; and a differential amplifier (50) ; wherein the adaptive gain control means (40) is configured to optimize the output from both sensors (10, 20) for light compensation, by way of equalizing the light coefficient factor (β, a) by both sensors (10,20) .
In another aspect of the present invention, a method for use in eliminating light interruption in a sensing system; said method comprising the steps of: providing at least one sensor configured for measuring samples; providing at least one sensor configured for detecting light; direct
both sensors to a differential circuit; optimizing the output from the sensor for detecting light for light compensation effect; equalizing the light gains from both sensors and producing zero light effect signals.
Brief Description of the Drawings
Other objects, features, and advantages of the invention will be apparent from the following description when read with reference to the accompanying drawings. In the drawings, wherein like reference numerals denote corresponding parts throughout the several views : FIG 1 (a) and FIG 1 (b) shows the effects of light in a sensing arrangement and the effects of filtering the light from the sample respectively;
FIG 2 shows the sensors arrangement involved in the system and method in accordance to a preferred embodiment of the present invention;
FIG 3 shows the overall view of the system and method in accordance with a preferred embodiment of the present invention. De-tailed Description of the Preferred Embodiments In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known methods, procedures and/or components have not been described in detail so as not to obscure the invention. Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
Referring to FIG 2 and FIG 3, the arrangement of system and method of the present invention in accordance with a preferred embodiment of the present invention comprises at least two sensors (10, 20), at least one analog read-out circuitry (30), at least one adaptive gain amplifier means and photo element (40) and differential amplifier circuit (50) .
From the above and still referring to FIG 1, out of the two sensors (10, 20) , at least one sensor is a chemical ISFET sensor (10) and another sensor is a photo sensor (20) . It should be noted that both of these sensors are placed and thus connected to the components as mentioned abo
environment thereby understandably these sensors (1U, 2U) shares the same light source. The first sensor, being the ISFET chemical sensor (10) is dipped into a chemical solution being a sample. The second sensor (20) being a light sensor or photo sensor is exposed to the light source. Accordingly, the output of the ISFET chemical sensor (10) is heavily inclined on the ion concentration of the solution with some degree (a) of light effects. The output of the second sensor (20) as the photo sensor is thoroughly influenced by light. The obtained outputs are suitably channeled to differential circuit, said differential circuit which is referred herein as the differential amplifier circuit (50) .
In accordance with a preferred embodiment of the present invention, the differential circuit (50) comprises two input terminals - positive and negative, whereby the positive input is channeled from the first ISFET sensor (10) and the negative input is channeled from the second photo sensor (20) .
The adaptive circuit which comprises the adaptive gain amplifier and photo element (40) is an automatic gain control and functions primarily to adjust the magnification β equal to a. In this process, the precise coefficients are vital as to the opposite magnitude of both signals will cancel each other, as modeled by the following equation: = light coefficient factor in sensor 1
ight coefficient factor in sensor
SI = Signal + a light
S2 = β light
Let assume a = β
Output = SI - S2
gnal + light) - light
= Signal
From the above the output of the differential circuit is a light free or zero light effects signal.
It is duly noted that the ISFET sensor (10) is configured to detect at least the pH level of the solution, whereby the output is a level of ion concentration and as discussed previously, some light interference in the solution. Such condition typically causes significant DC shift, within the range of 50mV to lOOmV. The second sensor (20) which detects light provides output in the form of voltage level interference by the ambient light. Both signals are channeled to a differential amplifier (50) .
As discussed previously, the adaptive gain control (40) of the photo sensor (20) aids to optimize the output of the appropriate light compensation effectively, by way of equalizing the β gain and a gain of the a:
result, the method of the present invention allows the better sensing capability for the ISFET sensor (10) due to the cancellation of light effect, thus producing zero light effect signals.
As will be readily apparent to those skilled in the art, the present invention may easily be produced in other specific forms without departing from its essential characteristics. The present embodiments is, therefore, to be considered as merely illustrative and not restrictive, the scope of the invention being indicated by the claims rather than the foregoing description, and all changes which come within therefore intended to be embraced therein.