Force sensing system and force sensor thereof

Abstract

The force sensor includes a first substrate, a second substrate, and a force-electric element. The first substrate has a clearance portion. The second substrate is disposed on the first substrate and has a suspension portion that at least partially covers the clearance portion. The force-electric element is disposed on the second substrate and has a first end portion disposed on the suspension portion of the second substrate. The suspension portion is configured to bend toward the clearance portion in response to an external force; wherein, in response to the external force, at least one electrical parameter of the force-electric element changes.

Description

[Technical Field]

[0001] This invention relates to a force sensing system and a force sensor applicable thereto; particularly to a force sensing system with a force-electric element and a force sensor applicable thereto. [Previous Technology]

[0002] Force sensors convert mechanical force into electrical signals, thereby enabling precise measurement and control of force. They have wide applications and play an important role in various fields. For example, force sensors can measure pressure, torque, or acceleration, and are correspondingly applied to motion analysis or weight measurement.

[0003] In recent years, force sensors have also been applied to biosignal sensing in healthcare (e.g., pulse pressure) or to high-precision measurement applications such as automation control (e.g., touch detection in robotic arms). As the application of force sensors has become more precise and miniaturized, both force sensors and the force sensing systems they are paired with will face challenges. [Summary of the Invention]

[0004] The present invention provides a mechanical sensing system and a mechanical sensor applicable thereto to effectively solve the above-mentioned problems.

[0005] One embodiment of the present invention provides a force sensor. The force sensor includes a first substrate, a second substrate, and a force-electric element. The first substrate has a clearance portion. The second substrate is disposed on the first substrate and has a suspension portion that at least partially covers the clearance portion. The force-electric element is disposed on the second substrate and has a first end portion disposed on the suspension portion of the second substrate. The suspension portion is configured to bend toward the clearance portion in response to an external force; wherein, in response to the external force, at least one electrical parameter of the force-electric element changes.

[0006] In one embodiment, the avoidance portion is a perforated hole that passes through the first substrate.

[0007] In one embodiment, the avoidance portion is a groove space formed on the first substrate.

[0008] In one embodiment, it further includes a flexible layer disposed between the electromechanical element and the second substrate.

[0009] In one embodiment, the second substrate has conductor lines that are electrically coupled to the electromechanical element.

[0010] In one embodiment, the electromechanical element further has a second end, the projection of the second end onto the first substrate not overlapping the avoidance portion.

[0011] In one embodiment, the at least one electrical parameter is the resistance value of the electromechanical element.

[0012] In one embodiment, the second substrate includes a body, the suspending portion extends from a connecting portion of the body, and the suspending portion has a free end opposite to the connecting portion; the electromechanical element has a long side direction, which is parallel to the direction in which the suspending portion extends from the body.

[0013] In one embodiment, the system surrounds the suspended portion.

[0014] In one embodiment, a U-shaped notch is formed between the body and the suspended part.

[0015] In one embodiment, a conductor line is provided on the body, and the conductor line extends at least partially along the U-shaped notch.

[0016] One embodiment of the present invention provides a force sensing system. The force sensing system includes a force sensor and a readout circuit. The force sensor includes a first substrate, a second substrate, and a force-electric element. The first substrate has a clearance portion. The second substrate is disposed on the first substrate and has a suspension portion that at least partially covers the clearance portion. The force-electric element is disposed on the second substrate and has a first end portion disposed on the suspension portion of the second substrate. The suspension portion is configured to bend toward the clearance portion in response to an external force; wherein, in response to the external force, at least one electrical parameter of the force-electric element changes. The readout circuit is electrically coupled to the force-electric element and configured to read the at least one electrical parameter of the force-electric element and determine the value of the external force based on the amount of change in the at least one electrical parameter.

[0017] In one embodiment, the avoidance portion is a perforated hole that passes through the first substrate.

[0018] In one embodiment, the avoidance portion is a groove space formed on the first substrate.

[0019] In one embodiment, it further includes a flexible layer disposed between the electromechanical element and the second substrate.

[0020] In one embodiment, the second substrate has conductor lines, and the reading circuit is electrically coupled to the electromechanical element via the conductor lines.

[0021] In one embodiment, the electromechanical element further has a second end, the projection of the second end onto the first substrate not overlapping the avoidance portion.

[0022] In one embodiment, the at least one electrical parameter is the resistance value of the electromechanical element, and the reading circuit includes at least one Wheatstone bridge.

[0023] In one embodiment, the second substrate includes a body, the suspending portion extends from a connecting portion of the body, and the suspending portion has a free end opposite to the connecting portion; the electromechanical element has a long side direction, which is parallel to the direction in which the suspending portion extends from the body.

[0024] In one embodiment, the system surrounds the suspended portion.

[0025] In one embodiment, a U-shaped notch is formed between the body and the suspended part.

[0026] In one embodiment, a conductor line is provided on the body, and the conductor line extends at least partially along the U-shaped notch.

[0027] In summary, the present invention discloses a circuit assembly as a force sensing system. The force sensing system includes the force sensor of the present invention. The force sensor has a second substrate, a first substrate, and a force-electric element. The second substrate has a suspension portion disposed on a clearance portion of the first substrate. The force-electric element is disposed on the suspension portion. When the force sensor is subjected to force, the suspension portion bends towards the clearance portion, causing the force-electric element disposed on the clearance portion to be subjected to bending tension. The magnitude of the force can be measured more sensitively through the suspension portion and the force-electric element. Furthermore, the first substrate provides mechanical structural support, and the deformation of the suspension portion of the second substrate after being subjected to force can be made more significant by the first substrate, thereby making the change in electrical parameters of the force-electric element itself due to force more obvious. The change in electrical parameters of the force-electric element due to force can be measured by the reading circuit of the force sensing system, and the force can be calculated thereby. The force-electric element and the reading circuit can be miniaturized through mature circuit manufacturing processes.

Implementation Method

[0040] The following description is an exemplary implementation of the invention, intended to describe the basic spirit of the invention, but not to limit the invention.

[0041] Any reference to elements referred to herein by names such as "first," "second," etc., does not generally limit the number or order of these elements. Rather, these names are used herein as a convenient way to distinguish two or more elements or instances of elements. Therefore, it should be understood that the names "first," "second," etc., in the claim do not necessarily correspond to the same names in the written description. Furthermore, it should be understood that references to first and second elements do not imply that only two elements can be used or that the first element must precede the second element. The terms "comprising," "including," "having," "containing," etc., as used herein are open-ended, meaning that they include but are not limited to.

[0042] In this invention, the terms "exemplary" and "for example" are used to mean "serving as an example, instance, or illustration." Any implementation or aspect described herein as "exemplary" or "for example" is not necessarily to be construed as preferred or advantageous over other aspects of the invention. The terms "about" and "approximately" as used herein with respect to specified values ​​or characteristics are intended to mean within a certain value (e.g., 10%) of the specified value or characteristic.

[0043] The force sensor of the present invention can be integrated, for example, into a medical sensing device. For instance, it can be integrated to measure blood pressure based on micropulsations on the body surface. Alternatively, the force sensor of the present invention can be integrated, for example, into the end of the gripper arm of a robotic arm as a sensor for touch sensing or gripping force sensing. It should be noted that the above applications are merely illustrative examples of the application areas of the force sensor of the present invention and do not limit the application fields or projects of the force sensor of the present invention.

[0044] One embodiment of the present invention provides a force sensor. As shown in FIG1, the force sensor 100 includes a first substrate 110, a second substrate 120, and a force-electric element 130. The first substrate 110 has a clearance portion 111. The second substrate 120 is disposed on the first substrate 110 and has a suspension portion 121 that at least partially covers the clearance portion 111. The force-electric element 130 is disposed on the second substrate 120 and has a first end portion 131 disposed on the suspension portion 121 of the second substrate 120.

[0045] The material of the first substrate 110 is, for example, a material with mechanical strength such as plastic, metal, fiberglass, glass, or composite material (e.g., FR-4, BT, ABF, or MIS). The clearance portion 111 of the first substrate 110 can be formed in the substrate material by machining (e.g., lathe). Alternatively, the first substrate 110 with the clearance portion 111 can also be produced by means of a mold, etc., and the present invention is not limited to the manufacturing method of the first substrate 110. The shape of the first substrate 110 is not limited to that shown in FIG. 1; the shape of the first substrate 110 can be square, circular, or any other suitable shape. Similarly, the shape of the clearance portion 111 of the first substrate 110 is not limited to that shown in FIG. 1; the shape of the clearance portion 111 of the first substrate 110 can be square, circular, or any other suitable shape. Furthermore, the shape of the first substrate 110 and the shape of the clearance portion 111 can be the same or different.

[0046] In one embodiment of the clearance portion, the clearance portion is a recessed space formed on the first substrate. Specifically, as shown in Figures 2A and 2B, the first substrate 110 has a first substrate surface 1101 and a second substrate surface 1102. A recessed space 112 is formed on the first substrate surface 1101. The bottom 1121 of the recessed space 112 does not contact the second substrate surface 1102; in other words, the recessed space 112 is a space formed by recessing from the first substrate surface 1101 toward the second substrate surface 1102 without penetrating the second substrate surface 1102. More specifically, the thickness (d1) of the first substrate 110 is the distance between the first substrate surface 1101 and the second substrate surface 1102, and the depth (d2) of the recessed space 112 recessed from the first substrate surface 1101 is less than the thickness (d1) of the first substrate 110. The depth of the recessed space 112 is preferably configured such that when the suspended portion 121 of the second substrate 120 bends towards the avoidance portion 111 after being subjected to force, it will not touch the bottom 1121 of the recessed space 112. In other words, as shown in FIG2B, the recessed space 112 is preferably configured not to interfere with the deformation trajectory (T1) of the suspended portion 121 of the second substrate 120 after being subjected to force. In addition, the electromechanical element 130 will undergo bending, stretching, or deformation after being subjected to force on the suspended portion 121. Therefore, the electrical parameters of the electromechanical element 130 will also change with the deformation of the suspended portion 121. By using the recessed space 112, which does not penetrate the first substrate 110, as the avoidance portion 111 on the first substrate 110, the structure of the first substrate 110 can be kept intact and complete mechanical support can be provided. Furthermore, the second substrate surface 1102 is flat because it does not have grooves, or the second substrate surface 1102 is not notched, which can provide support or protection against external forces or foreign objects from the outside of the second substrate surface 1102.

[0047] In one embodiment of the clearance portion 111, the clearance portion 111 is a cutout formed on the first substrate 110. Specifically, as shown in Figures 3A and 3B, the first substrate 110 has a first substrate surface 1101 and a second substrate surface 1102. A cutout 113 is formed in the first substrate 110 through the first substrate surface 1101 and the second substrate surface 1102. When the suspended portion 121 of the second substrate 120 is bent toward the clearance portion 111 after being subjected to force, it can deform without interference at the cutout 113. Through the setting of the cutout 113, the necessary thickness of the first substrate 110 can be greatly reduced, and the deformation of the suspended portion 121 of the second substrate 120 after being subjected to force can be free from interference by the first substrate 110. Therefore, the deformation amplitude of the suspended portion 121 of the second substrate 120 can be increased, so that the electromechanical element 130 on the second substrate 120 can generate a larger or more significant signal difference.

[0048] The second substrate 120 is a plate layer with less rigidity than the first substrate 110, or the elastic modulus of the second substrate 120 is greater than that of the first substrate 110. The material of the second substrate 120 is preferably selected to have insulating properties and mechanical strength (e.g., fracture resistance or crack resistance). In one embodiment, the material of the second substrate 120 is, for example, FR4, polyimide (PI), or polyester film (PET). It should be noted that the second substrate 120 and the first substrate 110 can also be made of the same material, and the elastic modulus, rigidity, or Young's coefficient of the second substrate 120 and the first substrate 110 can be adjusted by adjusting the substrate thickness. The second substrate 120 is disposed on the first substrate 110. Specifically, referring to FIG4, the second substrate 120 can, for example, be disposed on the first substrate surface 1101 of the first substrate 110, and the second substrate 120 at least covers the clearance portion 111 of the first substrate 110. The second substrate 120 can be disposed on the first substrate 110 by means of bonding, riveting, pressing, or screw fixing, but is not limited thereto. An exemplary definition of the suspended portion 121 of the second substrate 120 is a part of the second substrate 120 that is not supported by the first substrate 110. Specifically, as shown in FIG5, the second substrate 120 includes a body 122, the suspended portion 121 extends from a connecting portion 125 of the body 122, and the suspended portion 121 has a free end 1211 opposite to the connecting portion 125; the electromechanical element 130 has a long side direction 1301, which is parallel to the direction in which the suspended portion 121 extends from the body 122. The suspended portion 121 at least partially covers the clearance portion 111 and is connected to the body 122 of the second substrate 120 that is supported by the first substrate 110. The suspended portion 121 can have a notch 123 created on the second substrate 120 by means of cutting, but is not limited thereto. In one embodiment, the total length of the notch (l1+l2+l3) is preferably at least greater than the length (l4) of the portion connected to the substrate supported by the first substrate 110, so that the suspending portion 121 can deform more freely under stress. Furthermore, the invention is not limited to the shape of the suspending portion 121; the suspending portion 121 can be U-shaped, polygonal, triangular, or circular, as shown in FIG. 6.

[0049] In one embodiment, the body 122 of the second substrate 120 surrounds the suspension portion 121. However, in one embodiment, as shown in FIG7, the body 122 may not surround the suspension portion 121. The second substrate 120 has an edge 1201, and the edge 1201 has an edge notch 1202 with a connecting notch 123. The body 122 is positioned not around the suspension portion 121 through the edge notch 1202. By configuring the body 122 of the second substrate 120 to surround or not surround the suspension portion 121, different applications or force application methods can be provided.

[0050] The electromechanical element 130 is a component that generates a voltage or impedance change in a material, such as a piezoresistive or piezoelectric material, when subjected to mechanical stress (e.g., pressure or tension). The electromechanical element 130 is disposed on a second substrate 120 and has a first end portion 131 disposed on a suspension portion 121 disposed on the second substrate 120. Specifically, referring to FIG8, the electromechanical element 130 has a first end portion 131 and a second end portion 132. The first end portion 131 is disposed on the suspension portion 121, and the second end portion 132 is disposed on a portion of the second substrate 120 supported by the first substrate 110. Therefore, the projection P132 of the second end portion 132 onto the first substrate 110 does not overlap with the clearance portion 111. Thus, a portion of the electromechanical element 130 can be supported by the first substrate 110, while another portion will be subjected to mechanical stress following the trajectory of the suspension portion 121 as it deforms under force. When the electromechanical element 130 is subjected to mechanical stress (e.g., tensile / tensional stress generated between the suspension portion 121 of the second substrate 120 and the fixed portion due to deformation), its electrical parameters (e.g., voltage or impedance) will change due to material properties. Furthermore, compared to a configuration where the electromechanical element 130 is completely supported by the first substrate 110 (i.e., the electromechanical element 130 is not disposed in the suspension portion 121), the suspension portion 121 of the present invention can highlight the force applied to the electromechanical element 130, making the change in the electrical parameters of the electromechanical element 130 more significant. This improves the signal-to-noise ratio, accuracy, or detection limit during measurement (e.g., it allows the detection of smaller forces).

[0051] In one embodiment, the second substrate 120 has conductive lines that are electrically coupled to the force sensor 130. Referring to FIG9, the conductive lines 124 can be fabricated on the second substrate 120 by a circuit fabrication process, and the conductive lines 124 extend at least partially along the notch 123. The conductive lines 124 can be connected to the force sensor 130 via solder pads, wire bonding, or any conventional connection method. The conductive lines 124 on the second substrate 120 can improve the integration of the force sensor 100 and avoid circuit clutter. On the other hand, the yield and stability of the force sensor 100 can be improved by using mature circuit fabrication methods (e.g., etching, engraving, or photoresist processes). In this embodiment, a reference element 140 can also be disposed on the second substrate 120. The reference element 140 is electrically connected to the force sensor 130 and forms a circuit architecture such as (but not limited to) a comparator or a Wheatstone bridge. The reference element 140 is, for example, a resistor or a capacitor, a component with known electrical parameters. When the force-electric element 130 undergoes a change in its electrical parameters (e.g., resistance) due to the force applied, the reference element 140 can be used as a reference for the electrical parameters, thereby highlighting the amount of change in the electrical parameters of the force-electric element 130.

[0052] In one embodiment, a flexible layer is further included between the electromechanical element 130 and the second substrate 120. Referring to FIG10, the material of the flexible layer 150 is, for example, polyimide (PI) or polyester film (PET). The mechanical rigidity of the flexible layer 150 is preferably between that of the first substrate 110 and the second substrate 120. The electromechanical element 130 is disposed (e.g., by surface welding or adhesion) on the flexible layer 150, and the flexible layer 150 is disposed (e.g., by adhesion) on the second substrate 120, thereby the flexible layer 150 can serve as an intermediary material between the electromechanical element 130 and the second substrate 120. The flexible layer 150 can, for example, improve the stability of the electromechanical element 130 disposed on the second substrate 120. In one embodiment, the electro-electric material can be bonded to the flexible layer 150 first, and then bonded to the second substrate 120 through the flexible layer 150. Therefore, the reliability of the electro-electric material can be improved in terms of processing or manufacturing process. On the other hand, when the electro-electric material is deformed under force, the flexible layer 150 can act as a buffer between the second substrate 120 and the electro-electric material, avoiding problems such as breakage of the electro-electric material due to excessive rigidity change.

[0053] In summary, the present invention discloses a force sensor 100, which includes a second substrate 120, a first substrate 110, and a force-electric element 130. The second substrate 120 has a suspension portion 121 disposed on a clearance portion 111 of the first substrate 110. The force-electric element 130 is disposed on the suspension portion 121. When the force sensor 100 is subjected to force, the suspension portion 121 will bend toward the clearance portion 111, thereby causing the force-electric element 130 disposed on the clearance portion 111 to be subjected to bending tension. The magnitude of the force can be measured more sensitively through the suspension portion 121 and the force-electric element 130. Furthermore, the first substrate 110 provides mechanical structural support, and the first substrate 110 can make the deformation of the suspension portion 121 of the second substrate 120 after being subjected to force more significant, thereby making the change in electrical parameters of the force-electric element 130 itself due to force more obvious.

[0054] One aspect of the present invention provides a force sensing system. Referring to FIG11, the force sensing system 10 includes the force sensor 100 of the present invention and a reading circuit 200. The reading circuit 200 is electrically coupled to the force-electric element 130 and configured to read at least one electrical parameter (EP) of the force-electric element 130, and to determine the value of the external force based on the change in the at least one electrical parameter (EP).

[0055] The reading circuit 200 is selected based on at least one electrical parameter of the force-electric element 130. For example, when the force-electric element 130 changes its electrical parameter to a resistance value due to force, the reading circuit 200 can be a circuit constructed using the voltmeter-ammeter method or a circuit constructed using a bridge circuit. Taking the voltmeter-ammeter method as an example, a known current source or voltage source can be used to supply power to the force-electric element 130 and measure the voltage value across the force-electric element 130 or the current value flowing through the force-electric element 130, thereby measuring the resistance change of the force-electric element 130. In one embodiment, the reading circuit 200 includes, for example, a bridge circuit such as a Wheatstone bridge. In this embodiment, the reading circuit 200 can use the resistance balance principle on the bridge composed of resistors to calculate the resistance change on the bridge using a variable resistor, or calculate the resistance change of the force-electric element 130 using a reference resistance value and the current flowing through the bridge. However, the force-electric element 130 of the present invention is not limited to resistance change, but can also be measured by selecting the corresponding reading circuit 200 through voltage or capacitance change.

[0056] In one embodiment, the reading circuit 200 is coupled to the computing element 300. The computing element 300 is, for example, an FPGA, microprocessor, processor, or ASIC with computing capabilities. The computing element 300 can infer the force on the force-electric element 130 based on the changes in electrical parameters of the force-electric element 130 measured by the reading circuit 200, and then infer the force on the force-electric element 130 through the correspondence established between the material properties of the force-electric element 130 and its electrical parameters. In this embodiment, the computing element 300 can also be an electronic device with computing capabilities, such as a computer or an industrial computer. Through analog-to-digital conversion, the changes in the electrical parameters EP of the force-electric element 130 measured by the reading circuit 200 are converted from analog values ​​to digital values ​​and provided to the electronic device. It should be noted that the above are just examples, and the computing element 300 is not limited to processing digital signals. The electronic device can perform calculations and obtain corresponding mechanical information through internally preset programs or instruction sets.

[0057] In summary, the present invention discloses a force sensing system 10, comprising a force sensor 100 and a reading circuit 200. The change in electrical parameters of the force-electric element 130 on the force sensor 100 due to force can be measured by the reading circuit 200 of the force sensing system 10, thereby calculating the force value to be measured by the force sensor 100. The force-electric element 130 and the reading circuit 200 can be miniaturized through mature circuit manufacturing processes.

[0058] The prior description of the invention is provided to enable those skilled in the art to make or practice the invention. Various modifications to the invention will be apparent to those skilled in the art, and the general principles defined herein can be applied to other variations or embodiments can be combined with or implemented individually without departing from the spirit or scope of the invention. Therefore, the invention is not intended to be limited to the examples described herein, but is accorded the widest scope consistent with the principles and novel features of the invention herein. [Simplified Explanation of the Diagram]

[0028] The accompanying drawings presented in this invention are intended to help describe various embodiments of the invention. However, to simplify the drawings and / or highlight what the drawings are intended to present, known structures and / or elements in the drawings may be drawn in a simple schematic manner or presented in an omitted manner. On the other hand, the number of elements in the drawings may be singular or plural. The accompanying drawings presented in this invention are only for illustrating these embodiments and not for limiting them.

[0029] Figure 1 is a schematic diagram of a force sensor in one embodiment of the present invention.

[0030] Figures 2A and 2B are schematic diagrams of a first substrate having a groove space to form an avoidance portion in one embodiment of the present invention.

[0031] Figures 3A and 3B are schematic diagrams of a first substrate having a hollow hole to form a clearance portion in one embodiment of the present invention.

[0032] Figure 4 is a schematic diagram of the layering of the second substrate and the first substrate in one embodiment of the present invention.

[0033] Figure 5 is a top view of the second substrate in one embodiment of the present invention.

[0034] Figure 6 is a schematic diagram of different implementations of the suspension portion of the second substrate in one embodiment of the present invention.

[0035] Figure 7 is a top view of the second substrate in one embodiment of the present invention.

[0036] Figure 8 is a schematic diagram of an embodiment of the present invention in which the electro-electric material is disposed on the second substrate.

[0037] Figure 9 is a schematic diagram of a second substrate having conductor lines and reference elements in one embodiment of the present invention.

[0038] Figure 10 is a schematic diagram of a flexible layer between the electro-electric material and the second substrate in one embodiment of the present invention.

[0039] Figure 11 is a block diagram of a mechanical sensing system in one embodiment of the present invention.

Claims

1. A force sensor, comprising: a first substrate having a clearance portion; a second substrate disposed on the first substrate and having a suspension portion at least partially covering the clearance portion; wherein the elastic modulus of the first substrate is smaller than the elastic modulus of the second substrate; a force-electric element disposed on the second substrate and having a first end portion disposed on the suspension portion of the second substrate; and a flexible layer disposed between the force-electric element and the second substrate; wherein... The suspension part is configured to bend toward the avoidance part in response to an external force, thereby causing a change in at least one electrical parameter of the electromechanical element.

2. The force sensor as described in claim 1, wherein the clearance portion is a perforation through the first substrate.

3. The force sensor as claimed in claim 1, wherein the clearance portion is a recessed space formed on the first substrate.

4. The force sensor as claimed in claim 1, wherein the second substrate has conductor lines electrically coupled to the force-electric element.

5. The force sensor as claimed in claim 1, wherein the force-electric element further has a second end, the projection of the second end onto the first substrate not overlapping the clearance portion.

6. The force sensor as claimed in claim 1, wherein the at least one electrical parameter is the resistance value of the force-electric element.

7. The force sensor as claimed in claim 1, wherein the second substrate includes a body, the levitation portion extends from a connection portion of the body, and the levitation portion has a free end opposite to the connection portion; the force-electric element has a long side direction that is parallel to the direction in which the levitation portion extends from the body.

8. The mechanical sensor as described in claim 7, wherein the system surrounds the suspension portion.

9. The force sensor as described in claim 7, wherein a U-shaped notch is formed between the body and the suspension portion.

10. The force sensor as claimed in claim 9, wherein the body is provided with conductor lines that extend at least partially along the U-shaped notch.

11. A force sensing system, comprising: a force sensor, comprising: a first substrate having a clearance portion; a second substrate disposed on the first substrate and having a suspension portion at least partially covering the clearance portion; a force-electric element disposed on the second substrate and having a first end portion disposed on the suspension portion of the second substrate; and a flexible layer disposed between the force-electric element and the second substrate; wherein, The suspension part is configured to bend toward the avoidance part in response to an external force; wherein, in response to the external force, at least one electrical parameter of the force-electric element changes; and a reading circuit is electrically coupled to the force-electric element and configured to read the at least one electrical parameter of the force-electric element, and to determine the value of the external force based on the amount of change of the at least one electrical parameter.

12. The mechanical sensing system as described in claim 11, wherein the clearance portion is a perforation through the first substrate.

13. The mechanical sensing system as claimed in claim 11, wherein the clearance portion is a recessed space formed on the first substrate.

14. The force sensing system as claimed in claim 11, wherein the second substrate has conductor lines and the reading circuit is electrically coupled to the force element via the conductor lines.

15. The force sensing system as claimed in claim 11, wherein the force-electric element further has a second end, the projection of the second end onto the first substrate not overlapping the clearance portion.

16. The force sensing system as claimed in claim 11, wherein the at least one electrical parameter is the resistance value of the force-electric element, and the reading circuit includes at least a Wheatstone bridge.

17. The force sensing system as claimed in claim 11, wherein the second substrate includes a body, the levitation portion extends from a connection portion of the body, the levitation portion having a free end opposite to the connection portion; the force-electric element has a long side direction parallel to the direction in which the levitation portion extends from the body.

18. The mechanical sensing system as described in claim 17, wherein the system surrounds the suspension portion.

19. The mechanical sensing system as described in claim 17, wherein a U-shaped notch is formed between the body and the suspension portion.

20. The mechanical sensing system as claimed in claim 19, wherein the body is provided with conductive lines that extend at least partially along the U-shaped notch.

Images