The present application claims priority from the Singapore patent application no. 10202011509T, the contents of which are incorporated herein in entirety by reference.

TECHNICAL FIELD

[0001] The present disclosure relates to object handling, and more particularly to tools and methods of manipulating micro-objects in a medium.

BACKGROUND

[0002] Conventional methods of holding and moving micro/nano-size objects are heavily dependent on the physical properties of the objects. For example, optical tweezers can be used only if the object is non-transparent. For example, magnetic tweezers are only feasible if the object is made from ferromagnetic materials. Tweezers are configured to work in threesome so that they can physically grasp the object in a tight grip. The range of movement achievable with such conventional methods is limited compared to the range of dexterous movements possible with human hands or robotic manipulators. However, neither the human hand nor the robotic manipulator can be scaled down to the micro-scale to handle micro/nano-size objects.

SUMMARY

[0003] In one aspect, the present disclosure provides a method of handling an object in a medium. The method includes providing a micro-finger configured to undergo a change in a pose of the micro-finger in response to an interaction with at least one laser beam trapping the micro-finger, wherein the micro-finger has an elongate body defining a length of the micro-finger, the elongate body being configured to provide a plurality of contact points with the object.

[0004] Optionally, the method as described above, further including providing two laser beams configured to trap the micro-finger at a first laser receiving portion and a second laser receiving portion of the micro-finger respectively, wherein the first laser receiving portion and the second laser receiving portion are spaced apart from one another along a length of the micro-finger; and with the micro-finger in contact with the obj ect at a contact point selected from the plurality of contact points, displacing at least one of the two laser beams such that the micro-finger undergoes a change in a pose of the micro-finger.

[0005] The method according to any described above, wherein at least one of the first laser receiving portion and the second laser receiving portion is spaced apart from a geometric center of the micro-finger. The method according to any described above, wherein the change in the pose of the micro-finger comprises a change in the contact point between the micro-finger and the object such that the object undergoes one or both of an angular displacement and a linear displacement. The method according to any described above, wherein the change in the pose of the micro-finger is concurrent with the contact point being unchanged relative to one or both of micro-finger and the object. The method according to any described above, wherein the change in the pose of the micro-finger comprises a displacement of the contact point along the length of the micro-finger.

[0006] The method according to any described above, wherein the object is disposed between the micro-finger and an abutment such that the change in the pose of the microfinger comprises a change in one or more of the following: the contact point, an orientation of the micro-finger relative to the object, and a position of the micro-finger. The method according to any described above, wherein each of the first laser receiving portion and the second laser receiving portion is spaced apart from the contact point. The method according to any described above, wherein the first laser receiving portion and the second laser receiving portion are disposed on the elongate body. The method according to any described above, wherein each of the first laser receiving portion and the second laser receiving portion is characterized by a refractive index greater than a refractive index of the medium.

[0007] The method according to any described above, wherein at least one of the first laser receiving portion and the second laser receiving portion comprises a curved surface. The method according to any described above, wherein at least one of the first laser receiving portion and the second laser receiving portion comprises a lateral surface. The method according to any described above, wherein the first laser receiving portion and the second laser receiving portion are coupled by a link, and wherein the link has a smaller cross-sectional dimension than either of the first laser receiving portion and the second laser receiving portion. The method according to any described above, wherein the micro- finger comprises at least three joints spaced apart from one another, each of the at least three joints being configured with a curved surface and having a refractive index greater than a refractive index of the medium.

[0008] The method according to any described above further including using one of the at least three joints to provide the contact point; and selecting two of another of the at least three joints to be the first laser receiving portion and the second laser receiving portion respectively. The method according to any described above, wherein the microfinger is a rod-shaped cell. The method according to any described above, wherein the cell is a Schizosaccharomyces-pombe cell.

[0009] In another aspect, the present disclosure provides a method of handling an object in a medium. The method includes providing a first micro-finger and a second microfinger, the first micro-finger and the second micro-finger being configured to contact the object at respective contact points, the respective contact points being spaced apart on the object; providing two laser beams configured to trap the first micro-finger at a first laser receiving portion and a second laser receiving portion of the first micro-finger respectively, the first laser receiving portion and the second laser receiving portion being spaced apart from one another along a length of the first micro-finger, the first microfinger having an elongate body; and with the two micro-fingers concurrently in contact with the object, displacing at least one of the two laser beams such that the first microfinger undergoes a change in a pose of the first micro-finger.

[0010] The method according to any described above, wherein at least one of the first laser receiving portion and the second laser receiving portion are spaced apart from a geometric center of the first micro-finger. The method according to any described above, including displacing one or both of the first micro-finger and the second micro-finger, wherein the first micro-finger and the second micro-finger are in a dynamic formation such that one or both of the first micro-finger and the second micro-finger undergo a change in a pose. The method according to any described above, wherein the change in the pose includes a change in at least one of the respective contact points such that the object undergoes either or both of an angular displacement and a linear displacement. The method according to any described above, wherein the change in the pose comprises a displacement of one of the respective contact points along the length of the first micro- finger.

[0011] The method according to any described above, wherein the change in the pose of the first micro-finger comprises a change in one or more of the following: (i) a contact point between the first micro-finger and the object, and (ii) a contact point between the second micro-finger and the object. The method according to any described above, the change in the pose of the first micro-finger comprises a change in an orientation of the first micro-finger relative to one or both of the object and the second micro-finger. The method according to any described above, wherein the change in the pose of the first micro-finger includes a change in a position of the first micro-finger relative to one or both of the object and the second micro-finger. The method according to any described above, wherein each of the first laser receiving portion and the second laser receiving portion is spaced apart from the respective contact points.

[0012] The method according to any described above, including selecting a respective point on each of the first micro-finger and the second micro-finger as the respective contact points; and selecting at least two surface areas from each of the first micro-finger and the second micro-finger for use as the first laser receiving portion and the second laser receiving portion respectively. The method according to any described above, wherein each of the at least two surface areas define a joint having a refractive index greater than a refractive index of the medium. The method according to any described above, wherein at least one of the first micro-finger and the second micro-finger is a rodshaped cell. The method according to any described above, wherein the rod-shaped cell is a Schizosaccharomyces-pombe cell.

[0013] Also disclosed is a system configured to handle an object in a medium. The system includes a first micro-finger and a second micro-finger, each of the first micro-finger and the second micro-finger having a geometric center and each of the first micro-finger and the second micro-finger being configured to contact the object at a contact point; and each of the first micro-finger and the second micro-finger having a first laser receiving portion and a second laser receiving portion, the first laser receiving portion and the second laser receiving portion being spaced apart from one another and from the geometric center of the respective first micro-finger and second micro-finger, wherein the first micro-finger and the second micro-finger are configured in a dynamic formation to perform the method according to any described above.

[0014] Also disclosed is a device configured to handle an object in a medium. The device includes an elongate body having a first laser receiving portion and a second laser receiving portion, the first laser receiving portion and the second laser receiving portion being spaced apart from one another, at least one of the first laser receiving portion and the second laser receiving portion being spaced apart from a geometric center of the elongate body; and a surface of the elongate body, the surface being configured to provide a plurality of contact points with the object, the plurality of contact points being distributed along a length of the elongate body. The method according to any described above, wherein at least one of the plurality of contact points is disposed at a tip of the elongate body.

[0015] In another aspect, there is disclosed a device configured to handle an object in a medium. The device includes an elongate body configured to provide a plurality of contact points with the object, wherein the elongate body is configured to undergo a change in a pose in response to an interaction with a laser beam trapping the device. The device according to the above, wherein the device is an inanimate micro-object. The device according to any described above, wherein the device is a rod-shaped cell. The device according to any described above, wherein the elongate body of the rod-shaped cell is defined by a cell wall. The device according to any described above, wherein the rod-shaped cell is a Schizosaccharomyces-pombe cell.

BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. l is a schematic representation of a system for handling an object in a medium according to an embodiment of the present disclosure;

[0017] Fig. 2 is a magnified view of the object in the medium according to the embodiment of Fig. 1;

[0018] Fig. 3 is a schematic illustration of a method of micro-manipulate the object using no more than two micro-fingers according to an embodiment of the present disclosure;

[0019] Fig. 4 schematically illustrates examples of different movements achievable by the method of the present disclosure;

[0020] Fig. 5 is a schematic drawing illustrating more examples of movements achievable by the method of the present disclosure;

[0021] Fig. 6 is a schematic drawing illustrating yet another movement achievable by the method of the present disclosure;

[0022] Fig. 7 is a schematic drawing of another exemplary movement achievable by the method of the present disclosure;

[0023] Fig. 8 illustrates an example where a laser-driven micro-finger according one embodiment of the present disclosure is used in micro-manipulation;

[0024] Fig. 9 is a schematic flowchart of a method of micro-manipulation according to an embodiment of the present disclosure.

[0025] Fig. 10 is an isometric view of a first micro-finger and a second micro-finger for micro-manipulation according to an embodiment of the present disclosure;

[0026] Fig. 11 A is a top view of the micro-finger of Fig. 10 undergoing a change in pose;

[0027] Fig. 1 IB is a top view of the micro-finger of Fig. 10 undergoing another change in pose;

[0028] Fig. 12 is a partial view illustrating a dynamic formation of two micro-fingers of Fig. 10 in relation to an object;

[0029] Fig. 13 is a top view of a first micro-finger and a second micro-finger handling an object;

[0030] Fig. 14 is a partial view illustrating a change in a pose in the first micro-finger and/or the second micro-finger;

[0031] Fig. 15 is a top view of the first micro-finger and the second micro-finger handling the object in a medium;

[0032] Fig. 16 is a partial view illustrating a change in pose of the first micro-finger and/or the second micro-finger;

[0033] Fig. 17 is another top view of the first micro-finger and the second micro-finger handling the object;

[0034] Fig. 18 is a partial view illustrating a change in pose of the first micro-finger and/or the second micro-finger;

[0035] Fig. 19 is a schematic representation of three micro-fingers handling an object according one embodiment of the present disclosure;

[0036] Fig. 20 is a partial view illustrating a dynamic formation of the micro-fingers of Fig. 19;

[0037] Figs. 21A and 21B are images taken of another example of a first micro-finger and a second micro-finger handling an object according to an embodiment of the present disclosure;

[0038] Figs. 22A, 22B, and 22C are images taken of the micro-fingers of Fig. 21 A in a different formation with respect to the object being micro-manipulated; and

[0039] Figs. 23A and 23B are images taken of an example where more than two microfingers of Fig. 21 A are used in micro-manipulation of the object.

DETAILED DESCRIPTION

[0040] Reference throughout this specification to “one embodiment”, “another embodiment” or “an embodiment” (or the like) means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” or the like in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a thorough understanding of embodiments. One skilled in the relevant art will recognize, that the various embodiments be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, some or all known structures, materials, or operations may not be shown or described in detail to avoid obfuscation.

[0041] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. As used herein, the singular ‘a’ and ‘an’ may be construed as including the plural “one or more” unless apparent from the context to be otherwise.

[0042] Terms such as “first” and “second” are used in the description and claims only for the sake of brevity and clarity, and do not necessarily imply a priority or order, unless required by the context. The terms "about" and "approximately" as applied to a stated numeric value encompasses the exact value and a reasonable variance as will be understood by one of ordinary skill in the art, and the terms “generally” and “substantially” are to be understood in a similar manner, unless otherwise specified.

[0043] The terms “handling”, “manipulate”, and “micro-manipulation”, and their respective forms, are used interchangeably in the present disclosure, and refer holding or supporting an object while concurrently being capable of causing the object to undergo a change in location/position and/or orientation. A “pose” is used to collectively refer to a position and/or orientation of an object. As used herein, a change in pose may include a change in position (or location) or change in orientation or both. Using a laser beam to “trap” a device or part of a device refers to directing the laser beam at the device (or a specific part of the device) or having the laser beam intersect with the device. “Displacement” is used to refer to either or both of a linear displacement and an angular displacement. “Contact points” generally refers to points on surfaces on a device or a micro-finger which are suitable to contact the object. “Concurrent” or “concurrently” describes occurrences overlapping in time, the occurrences not necessarily beginning or ending at the same time.

[0044] Micro-manipulation refers to the manipulation of objects in the micro-world, including biological cells and micro/nanoparticles, etc. As illustrated in Fig. 1, disclosed herein is a setup 100 according to one embodiment of the present disclosure, configured to handle one or more objects in a medium, such that a greater range of handling movements are possible, i.e., so that micro-manipulation is achievable. In the present disclosure, the terms “object” and “micro-object” are used interchangeably and will be understood to refer to obj ects of a nano/micro-scale unless the context requires otherwise. The setup 100 includes a holder 200 and a laser source 310 coupled to a laser controller 320. The laser controller 320 is configured to control the laser source 310 and direct one or more laser beams 80 at a specific spot within the holder 200. A stage 410 is configured to support the holder 200. As an option, the setup 100 further includes a stage controller 420 coupled to the stage 410. The stage controller 420 is configured to move the stage 410 relative to the laser source 310 as part of focusing the one or more laser beams and/or to translate the holder in its entirety relative to the one or more laser beams. Alternatively, a relative movement between a laser beam 80 may be produced by a laser scanner and optical components.

[0045] Fig. 2 illustrates a partial and magnified view of contents in the holder 200 in a non-limiting example. The holder 200 may be configured to hold one or more objects 90/91/92 suspended or floating in a fluid medium 201. One or more micro-fingers (also referred to herein as one or more devices respectively), such as a first micro-finger 204 and a second micro-finger 205 are provided for micro-manipulation of the one or more objects 90/91/92. The objects 90/91/92 that can be manipulated by embodiments of the present disclosure can be of any material, including materials that are transparent, opaque, translucent, magnetic, non -magnetic, etc. As an example, the object 90 may be a biological cell and the medium 201 may be a saline solution. That is, the micro-fingers 204/205 are configured to handle one or more of the objects 90/91/92 in the medium 201. The objects 90/91/92 that can be manipulated using the micro-fingers and method of the present disclosure can be relatively small, e.g., a few micrometers or less) or relatively heavy (in the micro-scale).

[0046] Fig. 3 is a schematic drawing of a method of micro-manipulation according to an embodiment of the present disclosure. No more than two micro-fingers are necessarily to produce a wider range of controllable movements and produce the micro-manipulation described herein, although more than two micro-fingers may be used (and in some cases a single micro-finger suffices). In Fig. 3, a first micro-finger 204 and a second micro- finger 205 are schematically illustrated as having approximately similar size and shape, although in various other examples, they may differ in any one or more aspects, including in physical dimensions, material composition, organic/inorganic in origin, living/inanimate, or any combination thereof. The micro-fingers 204/205 or portions of the micro-fingers 204/205 may be made of but not limited to any one of silica, polystyrene, latex, etc., or a combination of any thereof. The sizes of the micro-fingers 204/205 may range from sub-micron to hundreds of micrometers. The micro-fingers 204/205 may also be cylindrical in shape with both the length and the radius in a range of a few micrometers to a few tens of micrometers. The micro-fingers 204/205 may have curved surfaces at either or both tips 282, or along at least a part of the lateral surface/lateral side 284. The micro-fingers 204/205 may be ovoid or have a oval-like cross-section. The micro-fingers 204/205 may have substantially flat surfaces at either or both tips 282, or along at least a part of the lateral surface/lateral side 284. As used herein, a “flat” surface is used in a general sense to describe a surface that is less curved than a spherical curved surface. A “flat” surface may refer to a surface with at least one planar portions. A “flat” surface may refer to a surface on which a plurality of contact points collectively define a substantially straight path/line (e.g., as illustrated in Fig. 7). A surface may be “flat” temporarily, or deformable between a more curved profile (e.g., 205a) and a flatter profile (e.g., 205c), in the course of the dexterous micro-manipulation provided under the present disclosure.

[0047] At least one of the two or more micro-fingers is configured as the first microfinger 204. The first micro-finger 204 may be described as having an elongate body defining a length (L) along a longitudinal axis 292 and a generally transverse dimension referred to as a width (W) of the first micro-finger 204, with the length being longer than the width. For convenience, the first micro-finger 204 is illustrated schematically as having a rotational symmetry about the longitudinal axis 292 and a reflective symmetry about a transverse axis 294, although various other examples of the first micro-finger 204 need not be of the symmetrical shape as illustrated herein. The elongate body includes a surface 296 configured to provide a plurality of contact points with the object 90. As an example, the plurality of contact points may be found distributed along the length of the elongate body. As another example, at least one of the plurality of contact points is disposed at a tip 282 of the elongate body. The first micro-finger 204 includes a first laser receiving portion 206 configured to receive a first laser beam, and a second laser receiving portion 208 configured to receive a second laser beam. The first laser receiving portion 206 and the second laser receiving portion 208 are disposed on the elongate body, spaced apart from one another by a separation (S) along the length (L)/longitudinal axis 292 of the first micro-finger 204. The second micro-finger 205 is shown with a corresponding first laser receiving portion 207 (selected to be distal relative to the object) and a second laser receiving portion 209 (selected to be proximal relative to the object). In some examples, at least one of the first laser receiving portion 206/207 and the respective second laser receiving portion 208/209 is spaced apart from a geometric center 293 of the respective micro-finger 204/205. In other examples, each of the first laser receiving portions 206/207 and the second laser receiving portions 208/209 are spaced apart from the respective contact points 202/203. In some examples, at least two surface areas from each of the first micro-finger and the second micro-finger are selected for use as the first laser receiving portion and the second laser receiving portion respectively. Over the course of multiple sequential micro-manipulation, the user may vary the selection of the at least two surface areas of the same micro-finger, e.g., including varying the separation (S) between the first laser receiving portion and the second laser receiving portion, etc.

[0048] Each of the first laser receiving portions 206/207 and the second laser receiving portions 208/209 are characterized by a refractive index greater than a refractive index of the medium. The setup 100 is configured to provide two laser beams 80 to trap the first micro-finger 204 at the first laser receiving portion 206 and the second laser receiving portion 208 respectively. As the two laser beams 80 are moved, the respective trapped laser receiving portions are moved. The first micro-finger 204 can be configured to undergo a change in a pose (position and/or orientation) of the first micro-finger 204 in response to an interaction with a first laser beam and a second laser beam trapping the first micro-finger 204. Movement of the first laser beam and the second laser beam causes the first micro-finger 204 to follow the movement of the laser beams, and thus the first micro-finger 204 undergoes a change in pose. In this manner, the first micro-finger 204 can be laser-actuated or can be laser-driven (i.e., capable of being moved, driven, actuated or otherwise operable by laser) so that its position and orientation are both controllable. The setup 100 may be configured to move both laser beams 80 together in the same velocity (speed and orientation) for the same displacement at the same time. The setup 100 may be further configured to provide a relative displacement and/or a relative velocity between the first laser receiving portion 206 and the second laser receiving portion 208. In other words, at least one or more micro-fingers 204/205 is configured to undergo a change in a pose of the micro-finger 204/205 in response to an interaction with at least one laser beam 80 trapping the micro-finger 204/205.

[0049] In some examples, the change in a pose of one or both of the micro-fingers 204/205 may include a linear displacement and/or an angular displacement. The change in the pose of the first micro-finger 204 may include a change in a position of the first micro-finger 204 relative to one or both of the object 90 and the second micro-finger 205. The change in the pose of the first micro-finger 204 may include a change in an orientation of the first micro-finger 204 relative to one or both of the object 90 and the second microfinger 205. Similarly, the change in the pose of the second micro-finger 205 may include a change in a position of the second micro-finger 205 relative to one or both of the object 90 and the first micro-finger 204. The change in the pose of the second micro-finger 205 may include a change in an orientation of the second micro-finger 205 relative to one or both of the object 90 and the first micro-finger 204. In some examples, the first microfinger 204 and the second micro-finger 205 may undergo respective changes in pose such that the object 90 undergoes linear displacement in the medium. Additionally or alternatively, the first micro-finger 204 and the second micro-finger 205 may undergo a change in pose such that the object 90 undergoes angular displacement in the medium.

[0050] Reference is also made to Fig. 4 to describe a range of dexterous micromanipulation made possible by embodiments of the present disclosure. The first microfinger 204 and the second micro-finger 205 may each be configured to be capable of translational motion and/or rotational motion. In some cases, the first micro-finger 204 and the second micro-finger 205 may cooperate to handle the object 90. In some cases, one or more of the first micro-finger 204 and/or the second micro-finger 205 may each be concurrently in contact with the object 90, and cooperatively and releasably engageable with the object 90. The micro-fingers 204/205 are each capable of three degrees of freedom, and can be laser-driven to cooperatively perform grasping, releasing, rolling, pinching or a combination of any of these tasks relative to the object 90.

[0051] Optionally, the second micro-finger 205 may concurrently be held stationary or be displaced, while in continuous or intermittent contact with the object 90. For example, the second micro-finger 205 may be trapped by a third laser beam directed at the first laser receiving portion 207 and a fourth laser beam directed at the second laser receiving portion 209 such that the second micro-finger 205 is held stationary relative to the first micro-finger 204.

[0052] Optionally, the second micro-finger 205 may be actuated or driven by the third laser beam and the fourth laser beam to move in an angular path 62. The first micro-finger 204 may be concurrently moved in the angular path 61 from an initial pose 204a to a next pose 204b, while the second micro-finger 205 is moved in the angular path 62 from an initial pose 205a to a next pose 205b. One or more of the micro-fingers may sequentially or concurrently be displaced in a third direction, for example, to a new subsequent pose 205c. Multiple micro-fingers 204/205 may undergo a change in their respective poses concurrently without the need to trap the object itself with a laser beam. There may be relative movement between all of multiple micro-fingers 204/205 and the object 90 without losing control of the position or orientation of the object 90, even if at any one instant of time there are fewer than two or three micro-fingers cooperatively positioning and/or orientating the object. The change in pose of the micro-fingers 204/205 (i.e., the change in both the position and orientation of the micro-fingers 204/205) may cause the object 90 to undergo an angular displacement 65 or a rotation about a centre of the object 90, without the centre of the object 90 undergoing linear displacement. The change in the pose of the micro-fingers 204/205 is concurrent with the contact point 202/203 being unchanged relative to one or both of micro-finger 204/205 and the object 90. In other words, with the change in a pose of the micro-fingers 204/205, the relative position between the object 90 and the micro-fingers 204/205 does not change while the object 90 experiences an angular displacement relative to the medium.

[0053] Optionally and concurrently with selected ones of other dexterous tasks, two of more of the micro-fingers, 204/205 may cooperatively pinch the object 90 therebetween. The micro-fingers selected to perform a pinching task advantageously do not need to be diametrically disposed about the object. For example, the micro-fingers 204/205 may be disposed in pose 204a and pose 205c respectively. This enables a greater degree of flexibility as the object may be located such that it is not possible to handle it from opposing sides of the object (e.g., when blocked by another object 91). These are more examples of the many dexterous manipulation unavailable previously through conventional means.

[0054] Fig. 5 schematically illustrates another possible micro-manipulation achievable by the dynamic formation of the micro-fingers. Instead of a tight grip on the object, one or more of the micro-fingers 204/205 contacting the object 90 can be made to slide relative to the object in a sliding engagement, concurrently or sequentially. For example, a plurality of contact points may be provided between the second micro-finger 205 and the object 90, along a line contact as the second micro-finger 205 slidably engage the surface of the object in moving from pose 205a to 205d. At any instant, the micro-finger 205 is provided to contact the object 90 at a contact point 203 selected from the plurality of contact points available on the respective surfaces of the micro-finger 205 and the object 90. The object 90 remains supported between the first micro-finger 204 and the second micro-finger 205 throughout the process, even when the first micro-finger 204 and the second micro-finger 205 are in non-parallel orientations (e.g., in poses 204a and 205d respectively).

[0055] Fig. 6 schematically illustrates yet another possible example of dexterous micromanipulation enabled by the micro-fingers 204/205. The change in a pose of the second micro-finger from an initial pose 205a to a next pose 205e corresponds to slidable engagement between the second micro-finger 205 and the object 90. This may be used to provide a micro-adjustment of the position of the object from an initial position 90 to a next position 95.

[0056] In another example as illustrated in Fig. 7, the first micro-finger 204 is displaced in a linear path 51 from an initial pose 204a to a next pose 204b. Concurrently, the second micro-finger 205 is displaced in another linear path 52 from an initial pose 205a to a next pose 205b. This can produce a rolling of the object 90 between the lateral sides 284 of the two micro-fingers 204/205. In other words, with the change in pose of the microfingers 204/205, the relative position between the object 90 and the micro-fingers 204/205 changes. The rolling motion corresponds to finding a plurality of contact points 202/203 distributed along the length (L) of the elongate body of the micro-fingers 204/205. The relative movement between the two fingers 204/205 may also be configured to create a spinning of the object 90 (without translational movement) or a rolling of the object 90 (with both rotational and translational movement). This rolling or spinning of the object 90 is another example of multiple dexterous manipulations unachievable through conventional means.

[0057] In other words, the first micro-finger 210 and the second micro-finger 220 may be configured in a dynamic formation relative to the object 90. In other words, the relative position between the first micro-finger 204 and the second micro-finger 205 may change during the change in pose for one or both of the micro-fingers 204/205. In a dynamic formation, it is possible to concurrently change a pose of one or more, or all, of the microfingers in contact with an object. For example, the first micro-finger 204 may undergo a linear displacement while the second micro-finger 205 undergoes an angular displacement. In another example, the first micro-finger 204 may undergo a linear displacement while the second micro-finger 205 is held stationary. In yet another example, the first micro-finger 204 may be moving in the linear path 51 at a different speed relative to the second micro-finger 205 moving in the linear path 52. the change in the pose of the micro-finger 204/205 comprises a change in the contact point 202/203 between the microfinger 204/205 and the object 90 such that the object 90 undergoes one or both of an angular displacement and a linear displacement. The dynamic formation is in contrast to a static formation. Relative to the object 90, a static formation refers to a formation in which all tweezer elements are in a fixed position relative to one another and to the object, e.g., conventional optical tweezers are required to be in a static formation so as to grasp the object without slippage or sliding movement between the tweezers and the object.

[0058] In some cases, the first micro-finger 204 may be used alone (e.g., without a second micro-finger 205) to manoeuvre an object 90. For example, as shown in Fig. 8, the object 90 is disposed between a micro-finger 204 and an abutment 270, such as another object. The change in the pose of the micro-finger 204 may involve a change in the contact point between the micro-finger 204 and the object 90. Alternatively or additionally, the change in the pose of the micro-finger 204 may include a change in an orientation of the microfinger 204 relative to the object 90. Alternatively or additionally, the change in the pose of the micro-finger 204 may include a change in a position of the micro-finger 204. Thus the micro-finger can be used to deliver a range of forces in different directions on the object 90, on different parts of the object 90.

[0059] As illustrated, it is possible to perform dexterous micro-manipulation using only two of the micro-fingers described herein, either or both of which are configured with three degrees of freedom in manipulation or movement. In some cases, it is even possible to use only one micro-finger to achieve the desired micro-manipulation. Dexterous manipulation (micro-manipulation) of an object 90 in a medium enabled by embodiments of the present disclosure includes but is not limited to: moving the object 90, rotating the object 90, concurrently moving and rotating the object 90, a combination of both moving and rotating the object 90, a sequential motion of moving (linearly translating) followed by a rotating of the object 90 in the medium, a sequential motion of rotating followed by moving (linearly translating) the object 90 in the medium, rolling the object 90 (rotation of the object about its own axis) in the medium, grasping/catching and/or releasing the object 90 in the medium, pinching the object 90, throwing (flicking, impacting or ejecting) the object 90 in the medium, etc.

[0060] Fig. 9 presents a schematic flowchart to describe a method 900 of handling an object in a medium according to an embodiment of the present disclosure. The method 900 includes providing two laser beams configured to trap the micro-finger 910, e.g., at a first laser receiving portion and a second laser receiving portion of the micro-finger respectively. The first laser receiving portion and the second laser receiving portion are spaced apart from one another along a length of the micro-finger. The method 900 may include providing a change in a pose of the micro-finger 920 in response to an interaction with at least one of the laser beams trapping the micro-finger. The micro-finger has an elongate body defining a length of the micro-finger, and is configured to provide a plurality of contact points with the object. The micro-finger may be provided to contact the object at a contact point selected from the plurality of contact points. The method 900 may include displacing at least one of the two laser beams such that the micro-finger undergoes a change in a pose of the micro-finger. For example, this may include displacing one of the laser beams relative to the other laser beam trapping the same microfinger, to produce a change in a pose of the micro-finger.

[0061] The method 900 includes providing two or more micro-fingers in a dynamic formation 930 for micro-manipulation of an object. For example, the method 900 of handling an object in a medium may be described as providing a first micro-finger and a second micro-finger, in which the first micro-finger and the second micro-finger are configured to contact the object at respective contact points, the respective contact points being spaced apart on the object. The method 900 may include providing two laser beams configured to trap the first micro-finger at a first laser receiving portion and a second laser receiving portion of the first micro-finger respectively. The first laser receiving portion and the second laser receiving portion are spaced apart from one another along a length of the first micro-finger, with the first micro-finger having an elongate body. For example, the method 900 may include, with the two micro-fingers concurrently in contact with the object, displacing at least one of the two laser beams such that the first micro-finger undergoes a change in a pose of the first micro-finger. For example, the method 900 may include, displacing one or both of the first micro-finger and the second micro-finger, wherein the first micro-finger and the second micro-finger are in a dynamic formation such that one or both of the first micro-finger and the second micro-finger undergo a change in a pose. For example, the method 900 may include, selecting a respective point on each of the first micro-finger and the second micro-finger as the respective contact points; and selecting at least two surface areas from each of the first micro-finger and the second micro-finger for use as the first laser receiving portion and the second laser receiving portion respectively.

[0062] Fig. 10 illustrates another embodiment of a micro-finger 210. The micro-finger 210 has an elongate body defining a length (L) of the micro-finger. The micro-finger 210 includes a first laser receiving portion 212 and a second laser receiving portion 214 disposed on the elongate body. The first laser receiving portion 212 and the second laser receiving portion 214 are spaced apart from one another along the length (L) of the microfinger. The first laser receiving portion 212 and the second laser receiving portion 214 are spaced apart by a first link 213. The first link 213 has a smaller cross-sectional dimension than either or both of the first laser receiving portion 212 and the second laser receiving portion 214. The first laser receiving portion 212 and a second laser receiving portion 214 are configured to be trapped by respective laser beams, such that the microfinger 210 may undergo a change in a pose. Each of the first laser receiving portion 212 and the second laser receiving portion 214 is characterized by a refractive index greater than a refractive index of the medium 201. [0063] In some embodiments, one or both of the first laser receiving portion 212 and second laser receiving portion 214 is configured as a sphere or configured with a spherical curved surface to enhance the trappability of laser beams on the laser receiving portions 212/214. The first link 213 may be configured with a lateral surface 284 extending from one laser receiving portion to another laser receiving portion. Each of the laser receiving portions 212/214 has a refractive index greater than a refractive index of the medium.

[0064] The micro-finger 210 may further include a third laser receiving portion 216. The second laser receiving portion 214 and the third laser receiving portion 216 are spaced apart from one another along the length (L) of the micro-finger. The second laser receiving portion 214 and the third laser receiving portion 216 may be spaced apart by a second link 215. The second link 215 has a smaller cross-sectional dimension than either or both of the second laser receiving portion 214 and the third laser receiving portion 216. The second link 215 may be configured with a lateral surface 284 extending from one laser receiving portion to another laser receiving portion. Similarly, the third laser receiving portion 216 may be configured to be trapped by respective laser beam. The third laser receiving portion 216 is characterized by a refractive index greater than a refractive index of the medium 201.

[0065] In some examples, one or more of the first, second or third laser receiving portions 212/214/216 may be provided with a plurality of contact points with the object 90. One or more of the first link and second link 213/215 may be provided with a plurality of contact points with the object 90. The contact points may be selected such that each of the plurality of contact points is spaced apart from a laser beam trapping the micro-finger 210, reducing a likelihood of the laser beam impinging directly on the object 90. The contact point may be selected by a user depending on the situation, prior to selecting the respective laser receiving portions 212/214/216 to be used for receiving one or more laser beams. The contact point(s) may be dynamically changed during the process of handling the object, providing flexibility in micro-manipulating the object 90.

[0066] In one example, the micro-finger 210 may include at least three joints 212, 214, 216 spaced apart from one another by respective links 213, 215. Each of the joints may be configured with a curved surface, such as a part of a spherical curved surface. Each of the joints may be configured with a refractive index greater than a refractive index of the medium. One of the at least three joints may be provided as a contact point. The other two joints of the micro-finger 210 may be configured as the first laser receiving portion 212 and the second laser receiving portion 214.

[0067] Fig. 11A illustrates a top view of the micro-finger 210 in the medium, with the first laser receiving portion 212 and the second laser receiving portion 214 trapped by a first laser beam and a second laser beam respectively. By moving both the first laser beam and the second laser beam such that the first laser receiving portion 212 and the second laser receiving portion 214 move with the same linear displacement 50, the micro-finger 210 undergoes the same linear displacement.

[0068] The micro-finger 210 may be made to undergo a change in orientation. For example, the second laser receiving portion 214 may be held stationary by the second laser beam, and the first laser receiving portion 212 may be concurrently moved/rotated about the second laser receiving portion 214 by the first laser beam. This angular displacement of the first laser (and correspondingly the first laser receiving portion) relative to the second laser beam (and correspondingly the second laser receiving portion) provides a change of a pose of the micro-finger 210 from an initial pose 216a to a next pose 216b.

[0069] In another example as shown in Fig. 11B, the first laser receiving portion 212 is held stationary by the first laser beam, and the second laser receiving portion 214 is concurrently moved/rotated about the first laser receiving portion 212 by the second laser beam. Moving the second laser beam causes a displacement to the second laser receiving portion 214. The micro-finger 210 undergoes an angular displacement or a rotation about the first laser receiving portion 212. This causes the micro-finger 210 and thus the third laser receiving portion 216 to angularly displace 60 about the first laser receiving portion 212, resulting in a change of a pose of the micro-finger from an initial pose 216a to a next pose 216c.

[0070] In the examples of Fig. 11A and Fig. 11B, the part of the micro-finger 210 that is used to contact the object may be interchangeably selected from any part of the microfinger. It can be seen that just these two non-limiting exemplary changes in pose of the micro-finger 210 can be used to provide a wide range of high-resolution micro- adjustments to the position and/or orientation of one or more objects. A user is thus provided with different options to controllably change the pose of the micro-finger 210, including accurate and relatively small rotations of the micro-finger 210. For example, the same third laser receiving portion 216 can be used to controllably perform a smaller displacement (from 216a to 216b) or a larger displacement (215a to 216c).

[0071] Fig. 12 illustrates an embodiment of a first micro-finger 210 and a second microfinger 220 handling an object 90 in a medium. The length (longitudinal axis) of the first micro-finger 210 is disposed substantially coaxially with the length (longitudinal axis) of the second micro-finger 220. The third laser receiving portions 216/226 are configured to contact the object 90. Each of the micro-fingers 210/220 are trapped by two laser beams at parts of the micro-fingers apart from the third laser receiving portions 216/226. The third laser receiving portions 216/226 may be disposed on opposing sides of the object 90 and in contact with the object 90. The first micro-finger 210 is displaced by a controlled relative movement between the first laser beam and the second laser beam such that the micro-fingers 210 move along curvilinear paths 61, from an initial pose 210a to a next pose 210b. Concurrently, the second micro-finger 220 may be moved along the path 62 from an initial pose 220a to a next pose 220b. The change in pose of the microfingers 210/220 (in this case change in both position and orientation of the micro-fingers 210/220) causes the object 90 to undergo an angular displacement 65 or a rotation about a centre of the object 90, without the centre of the object 90 undergoing linear displacement. The change in the pose of the micro-fingers 210/220 is concurrent with the contact point 211/221 being unchanged relative both the micro-fingers 210/220 and the object 90. This is one example of dexterous micro-manipulation not achievable using conventional means.

[0072] Figs. 13 and 14 illustrate another example of the first micro-finger 210 and the second micro-finger 220 handling an object 90 in a medium. In this example, the first micro-finger 210 may be disposed substantially parallel to the second micro-finger 220 (as shown in Fig. 13) or in a non-parallel configuration. The first micro-finger 210 is moved in a linear path 51 from an initial pose 210a to a next pose 210b, and the second micro-finger 220 is moved in a linear path 52 from an initial pose 220a to a next pose 220b. The third laser receiving portions 216/226 are configured to contact the object 90. The laser beams may be directed to trap the micro-fingers 210/220 with relatively low risk of the laser beams heating up the object beyond an acceptable threshold. The change in pose of the micro-fingers 210/220, e.g., change in the position of the micro-fingers 210/220, causes the object 90 to undergo an angular displacement 65 or a rotation about a centre of the object 90, with or without the centre of the object 90 undergoing linear displacement as desired by the user. The change in the pose of the micro-fingers 210/220 may include a displacement of the respective contact points 211/221 along the length of the micro-finger 210/220. In other words, with the change in pose of the micro-fingers 210/220, the relative position between the object 90 and the micro-fingers 210/220 changes, and the object experiences concurrent angular displacement relative to the medium. In another example, when the first micro-finger 210 displacing in the linear path 51 at a different speed relative to the second micro-finger displacing in the linear path 52, the object 90 can undergo both an angular displacement and a linear displacement. These are further examples of dexterous micro-manipulation not provided by conventional means.

[0073] Figs. 15 and 16 illustrate another example of a first micro-finger 210 and a second micro-finger 220 handling an object 90 in a medium. The second laser receiving portions 214/224 are configured to contact the object 90, with the laser beams trapping the microfingers 210/220 at parts of the micro-fingers 210/220 other than the second laser receiving portions 214/224. The micro-fingers 210/220 in this configuration advantageously enable application of a more uniform force on the object 90, with the contact points 211/221 disposed at respective midpoints of the micro-fingers 210/220. In the example shown in Fig. 16, the first micro-finger 210 is held stationary and the second micro-finger 220 undergoes a change in pose to move in a substantially linear path 52. In response, the object 90 is rolled along/about the second laser receiving portion 214, in which the rolling motion includes an angular displacement 67 as well as a linear displacement 57. The first micro-finger 210 and the second micro-finger 220 are thus in a dynamic formation relative to the object 90. In other words, the relative positions of the first micro-finger 210 and the second micro-finger 220 are changeable and/or there is a change in pose of at least one of the micro-fingers 210/220 concurrent with the holding/handling of the object by the micro-fingers 210/220 (without other support holding the object in place). The change in the pose may include a displacement of the respective contact points 211/221 along the object and/or at least one of the micro-fingers 210/220.

[0074] Figs. 17 and 18 illustrate another example of the first micro-finger 210 and the second micro-finger 220 handling an object 90 in a medium. The second links 215/225 are configured to contact the object 90. Alternatively, the first links 213/223 may be configured to contact the object 90. Any two of the three laser receiving portions of each micro-finger 210/220 may be configured to receive respective laser beams. As the second link 215/225 has a smaller cross-sectional dimension than both of the second laser receiving portion 214/224 and the third laser receiving portion 216/226, the second link 215/215 forms a “valley” with the respective laser receiving portions acting as abutment edges to better handle the object 90. Therefore, the micro-fingers 210/220 are configured to grasp the object 90 more securely while enabling a dynamic formation.

[0075] Figs. 19 and 20 illustrate an example in which more than two micro-fingers are used to handle an object 90. A first micro-finger 210, a second micro-finger 220 and a third micro-finger 230 are used to handle the object 90 in a medium. The first microfinger 210 is movable in a path 61 from an initial pose 210a to a next pose 210b, the second micro-finger 220 is movable in a path 63 from an initial pose 220a to a next pose 220b, and the third micro-finger 230 is movable in a path 62 from an initial pose 230a to a next pose 230b. The changes in pose of one or more of the micro-fingers 210/220/230 may occur concurrently. Alternatively, the change in pose of the micro-fingers 210/220/230 may occur sequentially and/or independently. The micro-fingers 210/220/230 provide a firm grasping force on the object 90 while still enabling a dynamic formation. As shown in Fig. 20, the change in pose of the micro-fingers 210/220/230 can be used to enable a series of micro-manipulation tasks including dynamic rolling, spinning, pinching, grasping, releasing or any combination thereof. These are additional examples of dexterous micro-manipulation not provided by conventional means.

[0076] In the foregoing, various examples of micro-fingers in the form of fabricated devices have been described. The method of dynamic micro-manipulation may be extended to the use of devices based on living (or once living) cells/organisms. Figs. 21A and 21B are images showing methods of using dynamic micro-manipulation tools in the form of living cells 250/260. A first device 250 and a second device 260, such as living cells, may be used to handle an object 90 in a medium, according to methods of the present disclosure. At least one of the devices 250/260 is selected from a cell having an elongate body. While the cell may not have easily distinguishable laser receiving portions and/or links, according to a method of the present disclosure, the cell is made to undergo a change in a pose using at least two lasers in interaction with the cell (device) 250/260. The change in pose of each or both of the devices 250/260 enable dynamic micro-manipulation of the object 90 as described in the foregoing. For example, as shown in the images of Figs. 22A to 22C, the method may include changing the pose of the devices 250/260 to cause the object 90 to undergo an angular displacement about a centre of the object 90. The method may include changing the pose of the devices 250/260 such that there is a displacement of respective contact points along the length of respective devices 250/260. As shown in the images of Figs. 23A and 23B, the method of the present disclosure may include using three devices 250/260/270 to clasp onto or grab the object 90 in the medium for dexterous micro-manipulation.

[0077] In some examples, one or both of the devices 250/260 are rod-shaped cells. The cells may be selected from cells with a cell wall 251/261. For example, the rod-shaped cell may be one selected from a culture of Schizosaccharomyces-pombe cells. In other examples, the devices 250/260 may be selected from an inanimate micro-object, a cell, or a combination thereof.

[0078] Also disclosed is a system configured to handle an object in a medium. The system includes at least a first micro-finger and a second micro-finger, each of the first microfinger and the second micro-finger having a geometric center and each of the first microfinger and the second micro-finger being configured to contact the object at a contact point. Each of the first micro-finger and the second micro-finger may have a first laser receiving portion and a second laser receiving portion, with the first laser receiving portion and the second laser receiving portion being spaced apart from one another and from the geometric center of the respective first micro-finger and second micro-finger. The system provides the first micro-finger and the second micro-finger in a dynamic formation to handle the object, including but not limited to dynamic micro-manipulation tasks as described in the foregoing.

[0079] As can be appreciated from the foregoing, the various embodiments of the present disclosure enable the handling or manipulating of micro-objects (micro-manipulation) without risking damage to the micro-objects. It is known that a focused laser beam employed to “trap” or to “hold” living cells in place may cause irreversible damage to the cells, e.g., cause the cells to die from heat generated by the laser beam. Counterintuitively, the present disclosure provides a way of using devices (including but not limited to living cells) as tools of micro-manipulation. In other examples where the micro-object is relatively large and/or opaque, or for various reasons previously untrappable, embodiments of the present disclosure enable sufficient trapping forces to be applied while concurrently enabling the freedom for dexterous micro-manipulation, including previously unachievable tasks such as the rolling or pinching of micro-objects. Dynamic micro-manipulation is another example of handling tasks previously not achievable using conventional means.

[0080] All examples described herein, whether of apparatus, methods, materials, or products, are presented for the purpose of illustration and to aid understanding, and are not intended to be limiting or exhaustive. Various changes and modifications may be made by one of ordinary skill in the art without departing from the scope of the invention as claimed.