Piezoresistive tactile sensor based on MEMS

Abstract

The utility model provides a piezoresistive tactile sensor based on MEMS, comprising: a stress mechanism comprising a touchpad and an extrusion column, the extrusion column protruding out of the touchpad; the sensing mechanism comprises a supporting frame and cantilever beams, an extrusion space is arranged in the supporting frame, part of the cantilever beams are connected to the supporting frame, the other part of the cantilever beams are attached to the supporting frame to move, the extrusion columns correspondingly extrude the cantilever beams, and any cantilever beam is provided with a piezoresistor. According to the utility model, the support frame of the sensing mechanism can provide sufficient extrusion movement space for the cantilever beam, and three-dimensional relative movement between the support frame and part of the cantilever beam can be realized, so that the sensor has higher detection transmission precision and higher response speed. Compared with a conventional machining structure at the present stage, the touch sensor has the remarkable advantages of being flexible to use, high in precision, fast in response, long in service life, wide in application range and the like, and a new thought is provided for research and development of the touch sensor.

Description

TECHNICAL FIELD

[0001] The utility model relates to sensor technical field, concretely point to a kind of piezoresistive tactile sensor based on MEMS. BACKGROUND

[0002] Under the background of the rapid development of intelligent manufacturing and robot technology today, end gripper and dexterous hand as the key components of robot to perform complex tasks, its performance directly affects the operation efficiency and safety of the whole system. At present, although the flexible tactile sensor universally used by these devices has played an important role in improving the flexibility of robot operation, its limitations have gradually emerged.

[0003] Flexible tactile sensor can simulate the tactile function of human skin to a certain extent by using the characteristics of soft material, and realize the perception of object shape, hardness and other attributes. However, the durability and life of this sensor are short, which becomes the main bottleneck restricting its wide application. In the long-term use process, soft material is easy to wear and fatigue damage, especially in the environment of high strength and high frequency operation, the performance attenuation of sensor is more obvious. This not only leads to the increase of equipment maintenance cost, but also may affect the stable operation of production line.

[0004] In addition, the precision and reliability of flexible tactile sensor still need to be improved. Due to the particularity of its structure and material, the sensor is easy to be disturbed in the process of signal transmission and conversion, resulting in distortion of output signal. This uncertainty limits the application of end gripper and dexterous hand in high precision operation field to a certain extent, such as precision assembly, delicate surgery and other occasions, which puts forward higher requirements for the precision and reliability of sensor. SUMMARY

[0005] Therefore, the technical problem to be solved by the utility model is to overcome the problem of limited service life and practical range in the prior art, and to provide a piezoresistive tactile sensor based on MEMS.

[0006] To solve the above technical problems, the utility model provides a kind of piezoresistive tactile sensor based on MEMS, it includes: force mechanism, the force mechanism includes touch plate and multiple extrusion columns, multiple the extrusion column is respectively connected to the touch plate, and it is set out along the thickness direction of the touch plate;Induction mechanism, the induction mechanism includes support frame and multiple cantilever beams, the support frame inside is equipped with multiple extrusion space, multiple the cantilever beam is respectively connected to the support frame, and it is correspondingly extended into multiple the extrusion space, in the thickness direction of the support frame, part of the cantilever beam is connected to the support frame, the rest part of the cantilever beam is attached to the support frame, and it can be moved relative to the support frame, multiple the extrusion column can extrude multiple the cantilever beam, to make it move in corresponding the extrusion space, at least one piezoresistor is equipped on any the cantilever beam.

[0007] In an embodiment of the utility model, the force mechanism further includes anchor column, the anchor column is arranged in the center of the touch plate, and extends in the same direction with the extrusion column, the anchor column is keyed to the support frame.

[0008] In an embodiment of the utility model, the support frame includes center part, edge part and multiple connecting parts, the edge part is arranged at intervals around the center part, multiple the connecting parts connect the center part and the edge part, to divide the support frame into multiple extrusion spaces, wherein the cantilever beam is connected to the center part, and extends in corresponding the extrusion space towards the edge part.

[0009] In an embodiment of the utility model, four cantilever beams are provided in the induction mechanism, the four cantilever beams are evenly spaced, and four extrusion spaces symmetrically arranged are provided in the support frame.

[0010] In an embodiment of the utility model, the cantilever beam includes beam body and contact part, one end of the beam body is connected to the support frame, the other end extends into the extrusion space, and is connected to the contact part, at least part of the contact part is set outwards by the extension end of the beam body in the plane of the support frame, and the extrusion column correspondingly extrudes the contact part.

[0011] In an embodiment of the utility model, the thickness of the beam body is less than the thickness of part of the support frame connected thereto, and in the thickness direction of the support frame, the upper surface of the beam body is connected to the support frame, and the lower end of the support frame can be attached to the support frame for movement.

[0012] In an embodiment of the utility model, the induction mechanism further includes solder pad and wire, the solder pad is arranged at the edge of the support frame, and is connected to the piezoresistor through the wire.

[0013] In one embodiment of the utility model, the projection area of the touchpad on the support frame is less than the projection area of the support frame in the same direction.

[0014] In one embodiment of the utility model, it further includes a mounting plate, the mounting plate and the stress mechanism are connected to the two sides opposite in the thickness direction of the induction mechanism respectively, and the mounting plate is connected with the external mounting surface.

[0015] The above technical scheme of the utility model has the following advantages compared with the prior art:

[0016] The MEMS-based piezoresistive tactile sensor has a higher detection transmission precision and a faster response speed, and the stress mechanism replaces the traditional flexible material, so that the sensor has a more stable operation structure and a longer service life. Compared with the conventional processing structure at the present stage, the application has the advantages of flexible use, high precision, fast response, long service life and wide application range, and provides a new idea for the research and development of tactile sensors. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to make the content of the utility model more easily understood, the utility model will be further described in detail in combination with the drawings according to the specific embodiments of the utility model.

[0018] Figure 1 is the three-dimensional structure schematic view of the MEMS-based piezoresistive tactile sensor in the preferred embodiment of the utility model;

[0019] Figure 2 is Figure 1 the three-dimensional structure schematic view of the stress mechanism in the MEMS-based piezoresistive tactile sensor shown in the figure;

[0020] Figure 3 is Figure 1 the three-dimensional structure schematic view of the induction mechanism in the MEMS-based piezoresistive tactile sensor shown in the figure;

[0021] Figure 4 is Figure 1 the three-dimensional structure schematic view of the induction mechanism in the MEMS-based piezoresistive tactile sensor shown in the figure;

[0022] Figure 5 is Figure 4 the enlarged structure schematic view of A in the figure.

[0023] The description of the drawings is as follows: 100, stress mechanism; 110, touch plate; 120, anchor column; 130, extrusion column; 200, induction mechanism; 210, support frame; 211, center part; 212, edge part; 213, connecting part; 214, extrusion space; 220, cantilever beam; 221, beam body; 222, contact part; 230, pressure sensitive resistor; 240, solder pad; 250, wire; 300, mounting plate. DETAILED DESCRIPTION

[0024] The present application will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present application and implement it. The embodiments are not intended to limit the present application.

[0025] EMBODIMENT

[0026] The embodiment provides a MEMS-based piezoresistive tactile sensor, which comprises a stress mechanism 100, the stress mechanism 100 comprising a touch plate 110 and a plurality of extrusion columns 130, the plurality of extrusion columns 130 being connected to the touch plate 110 respectively and being arranged in a convex manner along the thickness direction of the touch plate 110; and an induction mechanism 200, the induction mechanism 200 comprising a support frame 210 and a plurality of cantilever beams 220, the support frame 210 being internally provided with a plurality of extrusion spaces 214, the plurality of cantilever beams 220 being connected to the support frame 210 respectively and extending into the plurality of extrusion spaces 214 correspondingly, in the thickness direction of the support frame 210, part of the cantilever beams 220 are connected to the support frame 210, and the rest of the cantilever beams 220 are attached to the support frame 210 and can move relative to the support frame 210, the plurality of extrusion columns 130 can extrude the plurality of cantilever beams 220 so that they move in the corresponding extrusion spaces 214, and at least one pressure sensitive resistor 230 is arranged on any of the cantilever beams 220.

[0027] The piezoresistive tactile sensor based on MEMS realizes high-precision response to force in different directions through the extrusion cooperation of the plurality of extrusion columns 130 in the stress mechanism 100 and the cantilever beam 220 in the induction mechanism 200, wherein the support frame 210 of the induction mechanism 200 can provide sufficient extrusion movement space for the cantilever beam 220, and three-dimensional relative movement can be realized between the support frame 210 and part of the cantilever beam 220, so that the piezoresistive tactile sensor based on MEMS has higher detection transmission precision and faster response speed, and meanwhile, the stress mechanism 100 replaces the traditional flexible material, so that the sensor has a more stable working structure and a longer service life.

[0028] In the embodiment, the stress mechanism 100 is used to receive external force, which can transmit the force to the induction mechanism 200 through deformation, drive the corresponding cantilever beam 220 to deform, and then realize pressure detection through the piezoresistive resistor 230 on the cantilever beam 220. Further, in order to improve the connection and use stability of the piezoresistive tactile sensor based on MEMS, the embodiment further comprises a mounting plate 300, wherein the mounting plate 300 and the stress mechanism 100 are connected to opposite sides of the induction mechanism 200 in the thickness direction respectively, and the mounting plate 300 is connected to an external mounting surface.

[0029] Referring to FIGS. 1 to 3, Figure 1 and Figure 2 It is shown that the base material of the stress mechanism 100 in the embodiment is preferably a silicon wafer with <100> crystal orientation. The touch plate 110 is preferably a flat rectangular element, and one side of the touch plate 110 facing the induction mechanism 200 is provided with four extrusion columns 130 and one anchor column 120, wherein the anchor column 120 is arranged at the center of the touch plate 110 and extends in the same direction as the extrusion columns 130, and the anchor column 120 is bonded to the support frame 210, thereby forming a stable connection relationship between the stress mechanism 100 and the induction mechanism 200.

[0030] Further, the four extrusion columns 130 in the embodiment are arranged at the middle of the four edges of the touch plate 110, and in different embodiments, the extrusion columns 130 can be configured in other quantities or arranged at other positions according to actual use requirements, and the utility model does not make specific limitation on this.

[0031] In the embodiment, the support frame 210 is used to provide a mounting connection platform for the cantilever beam 220 and the force receiving mechanism 100, which comprises a center part 211, an edge part 212 arranged at intervals around the center part 211, and a plurality of connection parts 213 connecting the center part 211 and the edge part 212 to divide the support frame 210 into a plurality of extrusion spaces 214. The cantilever beam 220 is connected to the center part 211 and extends towards the edge part 212 in the corresponding extrusion space 214. Specifically, in the embodiment, four extrusion columns 130 are provided with four extrusion spaces 214, and the two ends of any connection part 213 are connected to the four corner parts of the edge part 212 and the center part 211, respectively, thereby forming four symmetrical extrusion spaces 214 around the center part 211 for the corresponding four cantilever beams 220 to move under external force.

[0032] Further, the sensing mechanism 200 in the embodiment is provided with four cantilever beams 220 arranged at uniform intervals between the four cantilever beams 220, thereby achieving uniform collection of force acting in different directions. Any cantilever beam 220 comprises a beam body 221 and a contact part 222, one end of the beam body 221 is connected to the support frame 210, the other end extends into the extrusion space 214 and is connected to the contact part 222. At least part of the contact part 222 is arranged outwardly protruding from the extension end of the beam body 221 in the plane of the support frame 210, and the extrusion column 130 extrudes the contact part 222, thereby increasing the contact area between the cantilever beam 220 and the extrusion column 130, and further improving the response accuracy. Specifically, the cantilever beam 220 in the embodiment is preferably in a "T" shape. In different embodiments, the contact part 222 of the cantilever beam 220 can also be configured in other shapes as long as it can achieve the effect of increasing the contact area between the cantilever beam 220 and the extrusion column 130, and the utility model does not make specific limitations on this.

[0033] Further, in the embodiment, the thickness of the beam body 221 is less than the thickness of the part of the support frame 210 connected thereto. In the thickness direction of the support frame 210, the upper surface of the beam body 221 is connected to the support frame 210, and the lower end of the support frame 210 can be attached to the support frame 210 for movement. Based on this, the cantilever beam 220 can more easily move in three dimensions under external force, thereby further improving its response accuracy.

[0034] In this embodiment, two pressure sensitive resistors 230 are arranged on each of the two opposite cantilever beams 220, and one pressure sensitive resistor 230 is arranged on each of the remaining two opposite cantilever beams 220. The sensing mechanism 200 further comprises a solder pad 240 arranged at the edge of the support frame 210 and connected to the pressure sensitive resistors 230 through a wire 250. Further, the projection area of the touchpad 110 on the support frame 210 is smaller than the projection area of the support frame 210 in the same direction, so that the solder pad 240 and the wire at the edge 212 can be prevented from being damaged when an external force is applied.

[0035] The preparation process of the MEMS-based piezoresistive tactile sensor is as follows:

[0036] Step 1: select a single crystal silicon wafer with a thickness of 300 μm and a <100> crystal orientation, and a BF33 glass sheet with a thickness of 300 μm;

[0037] Step 2: grow a dense SIO2 film on the surface of the silicon wafer as a shielding oxide layer by dry oxygen process;

[0038] Step 3: complete P-type light doping and P-type heavy doping on the front surface of the silicon wafer by photolithography and ion implantation process;

[0039] Step 4: complete the preparation of the pressure sensitive resistor 230 and the reference resistor by atomic activation through high-temperature furnace tube annealing;

[0040] Step 5: remove the shielding oxide layer using a buffered oxide etching (BOE) solution;

[0041] Step 6: complete the preparation of the single-end fixed cantilever beam 220 on the back surface of the silicon wafer by photolithography and deep reactive ion etching process, so that part of the cantilever beam 220 is connected to the support frame 210, and the remaining part of the cantilever beam 220 is attached to the support frame 210 and can move relative to the support frame 210;

[0042] Step 7: anode bonding of the back surface of the silicon wafer and the bare glass sheet (lower cover plate);

[0043] Step 8: deposit SIO2 and SI3N4 on the front surface by PECVD to prepare a passivation layer;

[0044] Step 9: complete the front surface structure preparation by photolithography and reactive ion etching process;

[0045] Step 10: complete the connection of the front surface metal wire 250 and the injection area by magnetron sputtering, photolithography and metal dry etching process;

[0046] Step 11, making ohmic contact between the metal wire 250 and the ion-implanted region of the silicon by alloying process under nitrogen environment;

[0047] Step 12, depositing SIO2 on the front surface by PECVD to make a passivation layer to protect the surface elements of the chip;

[0048] Step 13, exposing the pad 240 for wire bonding by photolithography and reactive ion etching process;

[0049] Step 14, etching the front surface to the bonding surface by photolithography and deep reactive ion etching process to release the sensing cantilever beam 220, thus completing the preparation of the sensing mechanism 200;

[0050] Step 15, selecting a piece of N-type <100> single crystal silicon wafer with a thickness of 300 μm, and making protruding cylinders and a center cylinder by photolithography and deep reactive ion etching process, thus completing the preparation of the stress mechanism 100;

[0051] Step 16, connecting the stress mechanism 100, the sensing mechanism 200 and the mounting plate 300, thus completing the preparation of the MEMS-based piezoresistive tactile sensor.

[0052] In summary, the MEMS-based piezoresistive tactile sensor has high-precision response to forces in different directions through the extrusion cooperation between the multiple extrusion columns 130 in the stress mechanism 100 and the cantilever beam 220 in the sensing mechanism 200, wherein the support frame 210 of the sensing mechanism 200 can provide sufficient extrusion movement space for the cantilever beam 220, and three-dimensional relative movement can be achieved between the support frame 210 and the cantilever beams, so that the MEMS-based piezoresistive tactile sensor has higher detection transmission precision and faster response speed, and the stress mechanism 100 of the sensor replaces the traditional flexible material, so that the sensor has a more stable working structure and a longer service life. Compared with the conventional processing structure at the present stage, the application has the advantages of flexibility, high precision, fast response, long service life and wide application range, and provides a new idea for the research and development of tactile sensors.

[0053] Obviously, the above embodiments are only examples for clearly illustrating, and are not intended to limit the embodiments. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments are not required to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the utility model.

Claims

1. A MEMS-based piezoresistive tactile sensor, characterized by: The application relates to a touchpad, which comprises a force-receiving mechanism and a sensing mechanism. The force-receiving mechanism comprises a touchpad and a plurality of extrusion columns, wherein the extrusion columns are connected to the touchpad and protrude along the thickness direction of the touchpad. The sensing mechanism comprises a support frame and a plurality of cantilever beams, wherein the support frame is internally provided with a plurality of extrusion spaces, the cantilever beams are connected to the support frame and extend into the extrusion spaces, in the thickness direction of the support frame, part of the cantilever beams are connected to the support frame, and the rest of the cantilever beams are attached to the support frame and can move relative to the support frame, the extrusion columns can extrude the cantilever beams to move in the corresponding extrusion spaces, and at least one pressure-sensitive resistor is arranged on each of the cantilever beams.

2. The MEMS-based piezoresistive tactile sensor of claim 1, wherein: The force-receiving mechanism further comprises an anchor column arranged at the center of the touchpad and extending in the same direction as the extrusion columns, and the anchor column is in keyed connection with the support frame.

3. The MEMS-based piezoresistive tactile sensor of claim 1, wherein: The support frame comprises a center part, an edge part and a plurality of connecting parts, the edge part is arranged at intervals around the center part, the connecting parts connect the center part and the edge part to divide the support frame into a plurality of extrusion spaces, wherein the cantilever beams are connected to the center part and extend towards the edge part in the corresponding extrusion spaces.

4. The MEMS-based piezoresistive tactile sensor of claim 1, wherein: Four cantilever beams are arranged in the sensing mechanism, and the four cantilever beams are arranged at equal intervals, and the support frame is correspondingly provided with four symmetrically arranged extrusion spaces.

5. The MEMS-based piezoresistive tactile sensor of claim 1, wherein: The cantilever beam comprises a beam body and a contact part, one end of the beam body is connected to the support frame, the other end extends into the extrusion space and is connected to the contact part, at least part of the contact part is arranged outwardly protruding from the extension end of the beam body in the plane of the support frame, and the extrusion column extrudes the contact part.

6. The MEMS-based piezoresistive tactile sensor of claim 5, wherein: The thickness of the beam body is smaller than the thickness of part of the support frame connected thereto, and in the thickness direction of the support frame, the upper surface of the beam body is connected to the support frame, and the lower end of the support frame can move in contact with the support frame.

7. The MEMS-based piezoresistive tactile sensor of claim 1, wherein: The sensing mechanism further comprises a solder pad and a wire, the solder pad is arranged at the edge of the support frame and is connected to the pressure-sensitive resistor through the wire.

8. The MEMS-based piezoresistive tactile sensor of claim 1, wherein: The projection area of the touchpad on the support frame is smaller than the projection area of the support frame in the same direction.

9. The MEMS-based piezoresistive tactile sensor of claim 1, wherein: The application further comprises a mounting plate, the mounting plate and the force-receiving mechanism are respectively connected to the two sides of the sensing mechanism in the thickness direction, and the mounting plate is connected to an external mounting surface.

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