DESC:TECHNICAL FIELD:

The present disclosure relates in general to a micro scale joint. Particularly but not exclusively, the present disclosure relates to a micro-scale articulation mechanism. Further, embodiments of the present disclosure relates to the articulation mechanism employed in micro scale articulation system.

BACKGROUND:

Micro-scale joints are essential elements of micro-assembled structures. Advancements in micro-assembly technologies have spurred the development of a variety of joints such as snap-lock joint, key-lock joint, inter-lock joint, pin-joint, solder-assisted self-lock joint, and adhesive joint. These joints are broadly classified as articulated joints and fixed joints depending on whether they allow relative motion between the joined micro-structures or not. Fixed joints are usually used in fabrication of three-dimensional micro-structures, wherein high out-of-plane spatial resolution may be obtained by first fabricating the micro-structure in-plane, then detaching it from the substrate and subsequently assembling it out-of-plane by means of a fixed joint.

However, articulated joints find application in development of MEMS, micro-robots and manipulators, where, in combination with suitable actuation technique, controlled motion between the joined parts may be achieved.

Traditionally, micro-manipulators and micro-robots are fabricated from compliant mechanisms, since these systems avoid issues related to friction, wear and associated nonlinearities. Such manipulators have been employed as versatile tools for nanometer-scale imaging and manipulation, owing to their high precision, adequate stiffness and high mechanical bandwidth. Nevertheless, since articulated joints enables assembly of microstructures fabricated from conventionally incompatible materials and methods, they potentially enable the development of advanced manipulators and micro-robots. However, the development of active articulated joints for such applications has not been adequately investigated.

In conventional Atomic Force Microscope (AFM) the tip or needle is always pointed in downwards direction to measure the surface finish for the flat surfaces only. There is no mechanism present in the art which can be employed to measure surface finish of oval or concave shaped surfaces. The movement of the tip or the needle is not possible in the existing AFM. The tip of the conventional AFM is not designed to rotate in two axis simultaneously.

The present disclosure is directed to solve one or more problems stated above, or any other problem of the prior art.

SUMMARY:

One or more shortcomings of the prior art are overcome by a mechanism and a system as claimed and additional advantages are provided through the provision of assembly as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the present disclosure, an articulation mechanism is disclosed. The mechanism comprises a base plate defined with a cavity, a sphere positioned within the cavity, and an adhesive medium provided between the sphere and the cavity. The adhesive medium surrounds a portion of the sphere and holds the sphere within the cavity. Wherein, the adhesive medium is sensitive to temperature, and allows movement of the sphere in the cavity based on the raise in the temperature.

In an embodiment, the adhesive medium solidifies at room temperature and arrests movement of the sphere within the cavity by forming a meniscus around a portion of the sphere and the adhesive medium is at least one of epoxy resin, prepolymers, polymers.

In an embodiment, the sphere is responsive to magnetic fields and at least one probe tip is fixed to the surface of the sphere for orientation along a predetermined axis.

In another non-limiting embodiment of the disclosure, an articulation system is disclosed. The articulation mechanism comprises of a base plate defined with a cavity, a sphere positioned within the cavity, and an adhesive medium provided between the sphere and the cavity. The adhesive medium surrounds a portion of the sphere and holds the sphere within the cavity. Wherein, the adhesive medium is sensitive to temperature, and allows movement of the sphere in the cavity based on the raise in the temperature. The system also includes a plurality of magnetic coils positioned at predetermined locations surrounding the articulation mechanism, wherein each of the plurality of magnetic coils selectively generate magnetic field for movement of the sphere within the cavity.

In an embodiment, the system comprises at least one heating element provided proximal to the adhesive medium to heat the adhesive medium.

In an embodiment, the system comprises d a control unit associated with the plurality of magnetic coils for controlling the magnetic field generation for articulation of the articulation mechanism.

In an embodiment, the system comprises a gripper member configured in-between the plurality of magnetic coils, wherein the gripper member grips the articulation mechanism.

In yet another embodiment of the disclosure a method for operating an articulation mechanism is disclosed. The method comprises of supplying heat to an adhesive medium surrounding a portion of a sphere wherein the adhesive medium is sensitive to temperature, and allows movement of the sphere in the cavity based on raise in the temperature. The method also comprises of supplying power to at least one of the plurality of magnetic coils positioned at predetermined locations surrounding the articulation mechanism, wherein the plurality of magnetic coils generate the magnetic field for articulation of the articulation mechanism.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined together to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF FIGURES:

The novel features and characteristics of the disclosure are set forth in the description. The disclosure itself, however, as well as a preferred mode of use, further advantages thereof, will best be understood by reference to the following description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings wherein like reference numerals represent like elements and in which:

Figure. 1 illustrates a perspective view of an articulation mechanism according to an embodiment of the present disclosure.

Figures. 2 a-e illustrates schematic views of a micro-scale ball and socket joint, according to an embodiment of the present disclosure.

Figures. 3a-3c illustrates a force diagram of a sphere of the articulation mechanism.

Figures. 4a-4c illustrates optical micrographs illustrating deposition of resin droplet around cavity and the sphere (3) using a micro-pipette..

Figure. 5 illustrates schematic diagram of the articulation system employed with the articulation mechanism of Figure. 1.

Figure. 6 illustrates an experimental setup to magnetically actuate the mechanism of Figure. 1.

Figures. 7a and 7b illustrates rotation of sphere about X-axis as illustrated and about Y-axis.

Figures. 8a and 8b illustrates plot showing rotation of sphere versus applied external magnetic field in direction about X-axis and Y-.

Figures. 9a-9d illustrates various steps involved in fixing a tip on a sphere according to an embodiment of the disclosure.

Figures. 10a-10cSEM image of the articulation mechanism of Figures. 9a-9d.

Figures. 11a-11d illustrates top-view of a tip-less mechanism carrying an adhesive droplet around the cavity and the sphere attached on an probe tip.

Figure. 12a illustrates frequency response of the fabricated articulation mechanism .

Figure. 12 b illustrates oscillation amplitude versus tip-sample distance obtained using the mechanism.

Figure. 12c illustrates AFM image of the scanned calibration grating using the articulation mechanism

Figure. 12d illustrates cross-sectional view showing the step height of the calibration grating.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF THE DISCLOSURE:

The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other mechanism for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that an assembly, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. 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.

Embodiments of the present disclosure relates to the design, fabrication and evaluation of an active, lockable micro-scale articulation mechanism. More particularly the present disclosure relates to a micro-scale articulation mechanism which enables development of advanced micro-manipulators and micro-robots. A magnetic micro bead of spherical morphology acts as the sphere. A cavity acts as a housing for the sphere wherein the sphere seats along with an adhesive medium and together acts as a socket. The application of external magnetic field enables actively orienting the articulation mechanism in any desired direction. The articulation mechanism remains in a locked state at room temperature, and needs to be heated to unlock it and actuate it. Subsequently, the articulation mechanism may be employed to change the orientation to any degree, for example from 0° to 90° about X-axis and Y-axis.

One such application of the articulation mechanism (100), may include but not limiting to an atomic force microscope. In the atomic force microscope the articulation mechanism may be integrated to the probe thereby enabling active re-orientation of the probe tip (5) in three-dimensions. The mechanism may be employed to image a standard sample, and the resulting image is shown to be free of artifacts, thereby demonstrating the ability of the joint to firmly grip the probe tip (5) during imaging. The micro-scale articulation mechanism (100) may be one such type of articulated joint which enables precise multi-degree-of-freedom control of an end-effector. Such manipulators enable the development of micro-valves and active micro-mirrors. Further, the ability to actively lock the joints enables independent actuation of different joints of a micro-robot.

Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Wherever possible, same numerals will be used to refer to the same or like parts. The following paragraphs describe the present disclosure with reference to FIGS. 1 to 12.

Figure. 1 is an exemplary embodiment of the disclosure which illustrates a perspective view of the articulation mechanism (100). The mechanism (100) comprises a base plate (1), wherein a cavity (2) is defined on a base plate (1). A sphere (3) manufactured a magnetic responsive material rests in a cavity (2) such that it makes contact only with the edges of the cavity (2). Further, an adhesive may be poured into the cavity (2) and it forms a adhesive medium (4) when it comes in contact with the sphere (3). A probe tip (5) may be attached to a part of the sphere (3). The mechanism may be employed with a plurality of magnetic coils, like a first set of coils surround the articulation mechanism (100) in the horizontal direction and a second set of coils are provided at the top portion and the bottom portion of the articulation mechanism (100). The first set of coils and the second set of coils produce a magnetic field thereby influencing the articulation mechanism (100) to articulate.

Figures. 2 a – e illustrates the sphere (3) and socket joint of the articulation mechanism (100) . A spherical magnetic micro-particle acts as a sphere (3) which rests on a cavity (2) such that it makes contact only with the edges of the cavity (2). As illustrated in figure 2a adhesive medium (4) is poured into the cavity (2) such that, the adhesive medium (4) forms a meniscus between the sphere (3) and the substrate. The meniscus applies adhesive force to hold the sphere (3) firmly in place while the cavity (2) ensures that the sphere (3) does not roll when it rotates about its center. Thus, the cavity (2) and the adhesive medium (4) together act as the socket.

In order to actuate the mechanism, an external magnetic field may be applied along an axis other than the axis in which the magnetic moment of the sphere (3) is aligned thereby generating a torque which is experienced by the sphere (3). If the applied torque is large enough to overcome friction, then the sphere (3) will re-orient in a manner that it aligns its magnetic moment in the direction of the applied external magnetic field. To re-orient the sphere (3) about two axes independently, three dimensional (3-D) magnetic field may be applied. Also, to achieve a smooth rotation of the sphere (3) within the socket, the surface of the particle and the substrate on which the mechanism (100) has to be made are chosen to be hydrophilic. In the ideal case, the adhesive medium (4) may wet the particle uniformly, thus causing the rotational stiffness of the adhesive medium (4) to be zero.

Fig. 2b-e illustrates an alternate embodiment of the articulation mechanism (100), where a solid (i.e. wax or polymer) may be employed to grip the sphere (3) which may be melted. At room temperature, the material is in its solid state (Fig. 2(b)). However, upon application of heat (10), it liquefies, and allows the sphere (3) to be reoriented as discussed in the above paragraph (Fig. 2c, d). Finally, upon reorienting in the desired angle, the heating coils (10) may be turned off which freezes the magnetic moment of the sphere (3) to point in a new direction (Fig. 2(e)). The heat (10) necessary to liquefy the adhesive medium (4) in solid state may be provided either by a micro-heater or by an optical heating method. The proposed articulation mechanism (100) is simple in construction and requires only a micro-scale sphere (3) and an adhesive medium (4) to grip it within the socket. Therefore, it may be developed on any fabricated micro-structure and further may be employed to assemble micro-structures with two axes rotational degrees of freedom.

Figure. 3a illustrates a magnetic sphere (3) of radius r resting on a cavity (2), and surrounded by an adhesive medium (4). In order to hold the sphere (3) within the socket and prevent rolling of the sphere (3), two necessary conditions must be fulfilled. The conditions may include the adhesive medium (4) layer should apply adequate adhesive force, and the applied external magnetic torque should overcome friction effects between the sphere (3) and the socket.

As illustrated in Figure. 3 a, the angular position of the cavity (2) with respect to the center of the sphere (3) is ???while the position of the point of contact of the adhesive medium (4) with the sphere (3) is ???.

It may be assumed that, the adhesive medium (4) wets the sphere (3) and the substrate completely, so that its contact angle with both of them may be zero. Finally, since the lateral dimensions of the meniscus are larger than its height, it is assumed that the profile of the meniscus is approximately circular in the X-Z plane with radius ro . The radius ro of the adhesive medium (4)derived for a specified ?????? and r ?and is given by,
……………… ( 1 )
The adhesive force on the sphere (3) arises from the force applied by the adhesive medium (4) at its line of contact with the sphere (3), along with Young-Laplace pressure applied by the adhesive medium (4). The Young-Laplace pressure developed within the meniscus is approximately given by P = ?l (1/rsin?1-1/r_0) where ??is the surface tension of the liquid, while the downward force applied by the liquid along the line of contact is
2p? l rsin2 ?1. Thus, the net adhesive force applied by the adhesive medium (4) is given by
…………………… ( 2 )

While the adhesive force applied by the adhesive medium (4) holds the particle in place, during re-orientation, it may also prevents the particle from rolling out of the socket. When an external magnetic field B is applied to re-orient the sphere (3) of magnetic moment m, then the particle will re-orient within the socket as long as the applied external magnetic torque, tB =mxB is less than the restoring torque applied by the adhesive force, i.e. Fadhrsin????about the edge of the cavity (2) (Figure. 2(b)). Noting that |m?B| = mBsin??, where ??is the angle between the magnetic moment of the particle and the direction of the applied magnetic field, the necessary condition to prevent the sphere (3) from rolling out of the socket is given by,
? ????????????????????????????????????????????????????????????????????????

Further, while the sphere (3) re-orients, it should overcome the moment applied by frictional force Ff acting along the line of contact between the particle and cavity (2). The friction force is given by Ff ???FN , where F_N is the normal force acting at the point of contact, given by FN ?? F_adh / (2sin?2 ?) and ??is the coefficient of static friction. This can be ensured by applying external magnetic field, such that the generated magnetic torque is greater than the mechanical torque applied by the frictional force Ff
…………………………….. (4)
Therefore, if the applied external magnetic torque satisfies the conditions given in (3) and (4), then the sphere (3) will re-orient without rolling out of the socket.

Also, it is necessary to analyze the stiffness of the mechanism (100) along X, Y, and Z-axes when the developed sphere (3) and mechanism is employed for any applications such as in AFM (Atomic Force Microscope). This analysis is significant when the probe tip (5) interacts with a sample as there should not be any unintended displacement or reorientation of the probe tip (5), as any such unintended displacement of the tip’s position will introduce undesirable artifacts in the obtained AFM image.

In order to obtain the Z-axis stiffness of the mechanism, it is assumed that the tip-sample
interaction force Fz along the Z-axis, is less than the Fadh of the adhesive medium (4) gripper. Under this condition, the adhesive medium (4) acts as a rigid link, so that the overall stiffness of the mechanism becomes equal to the stiffness of the base plate (1). However, if Fz ??Fadh then the particle along with the probe tip (5) will detach from the socket. Therefore, it is required that Fadh be greater than the expected tip-sample interaction force along the Z-axis. Further, if the probe tip (5) experiences lateral force from the sample, i.e. along the X or Y-axis, then a torque of Fj ltip , where j=X,Y is experienced by the mechanism, where ltip represents the offset of the endpoint of the probe tip (5) from the axis of rotation of the mechanism as shown in Figure. 3(c). Therefore, the torque applied due to the lateral tip-sample forces results in re-orienting the particle and the probe tip (5). However, the probe tip (5) reorients only if the torque applied by the forces exceeds the torque generated by friction given in Eqn. (4), viz., ?Fadh r/2sin???. If it does not exceed this value, the tip will not reorient within the socket, thus making the lateral stiffness of the mechanism equal to that of the base plate (1) itself. In the second case, when the torque applied due to the sample forces is greater than the torque applied by the frictional force, then the tip reorients. However, since a magnetic field B is applied, any angular rotation ???would result in application of restoring torque ?mB???on the particle, and thus, would contribute to a linear stiffness given by
………………………………. ( 5 )

Thus, for this case, the effective stiffness of the mechanism (100) would be equal to the parallel combination of the lateral stiffness of the base plate (1) and the “magnetic stiffness” km.

Figure 4 illustrates the images of the micrographs showing the deposition of the resin droplet around the through-hole/cavity (2). As described in above paragraph, in order to fabricate the mechanism (100), a socket may be created on the cantilever/base plate (1) and then a sphere (3) made of magnetic particles is placed on it. The socket is designed by making a through-hole/cavity (2) on the cantilever/base plate (1) and by depositing adhesive medium (4) droplet around its circumference. The diameter of the through-hole/cavity (2) may be chosen to be less than the diameter of the magnetic particle/sphere (3) that needed to be picked-up. In an exemplary embodiment, a circular through-hole/cavity (2) of diameter about 30 µm is made on a cantilever/base plate (1) of dimensions, having length 450µm, width 60 µm and thickness 7 µm. The through-hole/cavity (2) may be fabricated by using Focused Ion Beam milling (FIB) (Helios Nano Lab 600i, FEI), where the material was removed by machining a circular pattern through the complete thickness of the cantilever/base plate (1). Milling operation was performed in two steps, firstly coarse milling was performed at high ion current with a circular pattern of diameter 29µm and secondly fine milling was performed at low ion current, were a concentric circular pattern of outer diameter 30µm and inner diameter of 29µm was used. The currents that were employed in the two steps were 72 nA and 0.23 nA respectively. The optical micrograph of the fabricated through-hole/cavity (2) is shown in Figure. 4 (a). Around the fabricated hole, a liquid droplet of volume about 10pL is deposited. In the present disclosure, the liquid used is epoxy resin (diglycidyl ether of bisphenol A). Thus, the fabricated through-hole/cavity (2) and the adhesive medium (4) form the socket, thereby constraining the magnetic particle/sphere (3) from rolling on the cantilever/base plate (1) and enables its smooth reorientation.

Further in the fabricated socket, a sphere (3) (MQP-S-11-9 magnet powder, Magnequench) of diameter about 50 µm is positioned using a micro-pipette, as shown in Fig. 4 (b). In order to visualize and measure the rotation of the sphere (3) within the socket, a tiny magnetic bead was attached on the (3). The fabricated articulation mechanism (100) with the tiny bead attached on the sphere is shown in Fig. 4 (c).

Figures 5 and 6 illustrates a schematic view of articulation system employed with a magnetically actuated articulation mechanism (100). As discussed earlier and as illustrated in figures 5 and 6, in order to actuate the articulation mechanism (100), a plurality of magnetic coils (7, 8) are aligned along the X-, Y- and Z-axis respectively. Figure. 6(a) shows the experimental setup while Figure. 6(b) shows the magnified view of the X- and Y- coils. Figure. 6 (c) shows the results of calibration of the plurality of magnetic coils (7, 8). The fabricated mechanism (100) mounted on a holder/gripper member (6) and positioned at the center of plurality of magnetic coils (7, 8). Further to re-orient the sphere (3) within the socket about X- and Y- axis, the currents through the plurality of magnetic coils (7, 8) were appropriately changed, such that the direction of magnetic field changes in the YZ- and XZ- plane, respectively.

Initially, the magnetic moment of the sphere (3) is aligned along the Z-axis and as the direction of the applied magnetic field is changed, the sphere (3) is re-oriented to point its moment along the direction of the applied field. The change in the pointing direction of the sphere (3) was noted from the corresponding change in the position of the micro-bead attached to the sphere (3).

Figures. 7 (a) and (b) shows the images when the sphere (3) was re-oriented about X- and Y- axis respectively. It is seen from the micrographs that it was possible to rotate the particle by about 90° in both the X-axis and Y-axis. This demonstrates the ability of the fabricated articulation mechanism (100) to re-orient about two axes independently. Further during re-orientation, it is seen form the figures that the sphere (3) does not roll out of the cavity (2). In order to quantify the angles of rotation of the bead due to the applied field, the angular displacement of the bead about the center of the sphere (3) were measured. Thus, for rotation about the X-axis, the angle was measured from the axis aa’ passing through the centers of the sphere (3) and the initial position of the bead (Figure. 7 (a)), while for rotation about the Y-axis, it was measured from the axis bb’ (Figure. 7b)).

Figure. 8 (a) and (b) illustrates the plot of mean angle of sphere rotation for these three cases as function of the applied magnetic field angle about X- and Y- axis respectively. The maximum standard deviation at each angular position during these three trials was about 2°. This attests to the repeatability in the response of the mechanism (100) to the commanded change in orientation. It is seen from the plots that initially the sphere (3) did not reorient till the external magnetic field direction reached to an angle of about 20°, thus creating a dead zone in the joint. But once the magnetic field angle increased more than 20° the sphere (3) started to re-orient almost proportionally with the change in the applied field angle. Therefore, this is indicative of the minimum torque required to start reorientation of the particle that arises due to frictional force acting at the point of contact between the sphere (3) and cavity (2).

Some of the other factors with regards to reorientation are the hysteresis in the contact angle, and pinning of the meniscus due to unevenness of the surface of the sphere (3). This dead zone also results in hysteresis in the response of the mechanism. However, it can be minimized by either appropriately coating the surfaces of the particle to make it smooth and hydrophilic or by using a different liquid that wets the particle uniformly without any hysteresis in its contact angle. It can also be eliminated by means of visual servo-control. Hence, the dead zone and hysteresis introduced in the fabricated mechanism is not a fundamental limitation of the joint design but a practical issue that can be addressed. Hence by attaching any micro-structure on the sphere (3) held within the socket, active re-orientation between the two micro-structures is enabled.

Figures. 9a and 9billustrates the design of cavity (2) on a tip-less mechanism with adhesive medium (4) around it and fragile beam (14) connecting an probe tip (5) with sphere (3) to the remaining base plate (1). A re-orientable mechanism is fabricated by integrating the micro-scale sphere (3) and socket joint on a tip-less mechanism wherein an probe tip (5) was attached to the sphere (3) and may be held in place using an adhesive medium (4) based gripper. In order to test the gripping capability of the adhesive medium (4), the fabricated re-orientable mechanism may be evaluated by performing AFM imaging. This is of significance because the lateral tip-sample forces acting at the probe tip (5) while imaging can potentially shear the adhesive medium (4) and detach the sphere (3) from the socket.

The schematic of a tip-less mechanism with the socket is shown in Figure. 9a. In order to pick up the sphere (3) with an integrated probe tip (5), the sphere (3) may be attached on a base plate (1), a neck may be fabricated on the base plate (1), and the sphere (3) may then be picked-up by breaking the fragile beam (14) using the adhesive force generated by the adhesive medium (4). The fragile beam may be of a length, width and thickness l1, w1 and t1 respectively and is offset from the probe tip (5) by a distance l0 (Figure. 9 (b)). It is desirable to pick the particle by applying adhesive force, and with minimum angular deflection of the fragile beam (14). The design of the fragile beam (14) is such that the beam is short, and placed well behind the probe tip (5). During pick up, the beam may be broken by virtue of the adhesive capillary force applied by the adhesive medium (4) formed between the particle and the cavity (2) (Figure. 9c). Once the beam is broken, the particle along with the probe tip (5) gets picked-up on the tip-less mechanism (Figure. 9 (d)).

In order to fabricate a re-orientable AFM probe, a socket may be created on the tip-less AFM probe
by following the steps discussed above. The scanning electron microscope (SEM) image of the fabricated cavity (2) on a tip-less AFM probe is shown in Figure. 10a. The SEM image of the fragile beam (14) is shown in Figures. 10b and 10c. For a fragile beam (14) fabricated from silicon, the force required to break this beam is calculated to be 0.19 µN. This force is small compared to the adhesive forces that the adhesive medium (4) gripper can apply 0.32 µN, hence the particle can be easily picked-up using the adhesive medium (4) gripper. After integrating the probe tip (5) onto the sphere (3), and fabricating the socket on a tip-less mechanism, the sphere (3) was picked up at the location of the cavity (2).

Initially a resin droplet of volume about 10pL is deposited around the fabricated through hole/cavity (2) on the tip-less mechanism and then it was aligned in the X-Y plane with respect to the magnetic particle/sphere (3) as shown in Figure. 11a. Then, the tip-less mechanism was positioned below the particle, such that the particle may be aligned with the through hole/cavity (2) on the tip-less mechanism and was offset from the mechanism only along the Z-axis, as shown in Figure. 11 b. In order to pick up the particle, the tip-less mechanism may be displaced along the Z-axis by means of a nano-positioner, to make contact with the particle and to allow the adhesive medium (4) to form meniscus between the mechanism and the magnetic particle/sphere (3). Finally, upon retracting the probe tip (5), the adhesive force applied by the adhesive medium (4) may break the fragile beam (14) and allowed the particle to be picked-up on the through hole/cavity (2) [Figure. 11c and d]. The fabricated magnetic particle/sphere (3) and socket joint on an AFM probe, shown in Fig. 11 (d) can now re-orient its probe tip (5) about two axes independently, using the magnetic actuation set-up discussed above.

In order to validate the applicability of the proposed magnetic particle/sphere (3) and socket joint in developing re-orientable AFM probe, AFM imaging of a standard calibration grating with periodic step-like topography (VGRP-15M, Bruker) may be performed. All the imaging is conducted in air at room temperature using a custom made, in-house AFM. In the developed AFM system, the actions related to actuation, measurement, and control may be performed by a real-time controller (DS 1103, d SPACE) operated at an update rate of 50 kHz.

The developed re-orientable AFM probe is employed to perform tapping-mode imaging of the calibration grating, by exciting the mechanism at the identified resonance frequency. The measured frequency response and the mechanism’s oscillation amplitude versus the tip-sample distance plots are shown in Figures. 12a and 12b respectively. The experimentally measured resonance frequency of the mechanism is 2.4 kHz and the tapping sensitivity is 38mV/µm. During imaging, the probe tip (5) is oriented using external magnetic field to point along the Z-axis, similar to a conventional AFM probe. However, in order to experimentally validate the gripping capability of the adhesive medium (4) based socket, the external magnetic field is switched off after initial alignment. Therefore, if the tip’s position were to change during imaging, then it will introduce artifacts in the topographic image. However, if there are no artifacts in the image then it is indicative of the fact that the adhesive medium (4) based socket has adequate stiffness to grip the sphere (3) firmly and hence can be employed for AFM imaging.

Figure. 12c shows the topographic image of the grating. It is seen from the obtained topographical image of the calibration grating that there are no artifacts in the image.

Further, Figure. 12d shows the profile of the grating. The measured step height obtained from the profile closely matches the nominal value of 180.6 nm provided by the manufacturer. In particular, it is seen that there are no artifacts near the vertical edges of each of the steps, where the magnitude of lateral forces on the tip is likely to be the highest. Therefore, the obtained artifact free topographic image demonstrates that the developed sphere (3) and socket joint also preserves the imaging capability of the AFM probe. In combination with the rotational degree of freedom enabled by the sphere (3) and socket joint, the mechanism can be used for performing advanced 3-D manipulation and metrology tasks.

In an embodiment, the articulation mechanism enables simultaneous two-axis rotational degrees of freedom between the joined parts and also can be employed to enhance access to three dimensional features during nano-metrology, or facilitate bottom-up assembly of advanced nano-system prototypes.

Equivalents:

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Referral Numerals:

Reference Numerals Description
100 Articulation mechanism
101 Articulation system
1 Base Plate
2 Cavity
3 Sphere
4 Adhesive medium
5 Probe Tip
6 Gripper Member
7 Plurality of Magnetic Coils
8 Plurality of Magnetic Coils
9 Heating element
10 Heat
12 Sample Stage
14 Fragile Beam

,CLAIMS:We Claim:
1. An articulation mechanism (100), comprising:
a base plate (1) defined with a cavity (2);
a sphere (3) positioned within the cavity (2);
an adhesive medium (4) provided between the sphere (3) and the cavity (2), the adhesive medium (4) surrounds a portion of the sphere (3) and holds the sphere (3) within the cavity (2), wherein, the adhesive medium (4) is sensitive to temperature, and allows movement of the sphere (3) in the cavity (2) based on raise in the temperature.

2. The articulation mechanism (100) as claimed in claim 1, wherein the adhesive medium (4) at room temperature solidifies, and arrests movement of the sphere (3) within the cavity (2).

3. The articulation mechanism (100) as claimed in claim 1, wherein the sphere (3) is responsive to a magnetic field.

4. The articulation mechanism (100) as claimed in claim 1, wherein the adhesive medium (4) is at least one of epoxy resin, prepolymers, polymers.

5. The articulation mechanism (100) as claimed in claim 1, comprises at least one probe tip (5) fixed on a surface of the sphere (3) for orientation along a predetermined axis.

6. The articulation mechanism (100) as claimed in claim 1, wherein the adhesive medium (4) forms a meniscus around the portion of the sphere (3) for holding the sphere (3) within the cavity (2).

7. An articulation system (101) comprising:
an articulation mechanism (100), the mechanism (100) comprising:
a base plate (1) defined with a cavity (2);
a sphere (3) positioned within the cavity (2);
an adhesive medium (4) provided between the sphere (3) and the cavity (2), the adhesive medium (4) surrounds a portion of the sphere (3) and holds the sphere (3) within the cavity (2) wherein, the adhesive medium (4) is sensitive to temperature, and allows movement of the sphere (3) in the cavity (2) based on raise in the temperature; and
a plurality of magnetic coils (7, 8) positioned at predetermined locations surrounding the articulation mechanism (100), wherein each of the plurality of magnetic coils selectively generate magnetic field for movement of the sphere (3) within the cavity (2).

8. The system (101) as claimed in claim 7, comprises at least one heating element (9) provided proximal to the adhesive medium (4) to selectively heat the adhesive medium (4).

9. The system (101) as claimed in claim 7, comprises a control unit (10) associated with the plurality of magnetic coils (7, 8) for controlling the magnetic field generation for articulation of the articulation mechanism (100).

10. The system (101) as claimed in claim 7, comprises of a gripper member (6) configured in-between the plurality of magnetic coils (7, 8), wherein the gripper member (6) grips the articulation mechanism (100).

11. A method for operating an articulation mechanism (100), the method comprising:
supplying heat from at least one heating element to an adhesive medium (4) surrounding a portion of a sphere (3), wherein the adhesive medium (4) is sensitive to temperature, and allows movement of the sphere (3) in the cavity (2) based on raise in the temperature;
supplying power to at least one of a plurality of magnetic coils (7, 8) positioned at predetermined locations surrounding the articulation mechanism (100), wherein the plurality of magnetic coils (7) generate magnetic field for articulation of the articulation mechanism.