MEMS sensors

Abstract

To provide an MEMS sensor which allows a contact part to be easily replaced to suite a use and a target object.SOLUTION: An MEMS sensor 1 is provided, comprising a sensor chip 3 sealed with an elastic resin 2 and a contact part 4 provided on the sensor chip 3, where the contact part 4 is removably fixed to the sensor chip 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to MEMS (Micro Electro Mechanical Systems) sensors. [Background technology]

[0002] As an example of a MEMS sensor, tactile sensors are gaining increasing attention for their use in collaborative robots, remote control, and other applications. Various technologies have been proposed for tactile sensors, but no standard technology has yet been established. Considering their affinity with human touch, tactile sensor devices with soft contact areas like human skin are required, and several technologies to achieve this have been proposed (for example, Patent Documents 1-3 and Non-Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-128940 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-208248 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-201061 [Non-Patent Document 1] H. Yokoyama et al., “Active Touch Sensing by Multi-axial Force Measurement Using High-Resolution Tactile Sensor with Microcantilevers,” IEEJ Trans. Sensors Micromachines, vol. 134, no. 3, pp. 58-63, 2014. Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have confirmed that the shape and material of the contact area significantly affect the detection of friction and surface irregularities in tactile sensation (see, for example, Non-Patent Document 1). Therefore, the contact area must be optimized depending on the application of the MEMS sensor. For example, in a tactile sensor in which the contact area is made of an elastic material and the sensor chip (detection unit) is encapsulated in the elastic material, the shape and material (e.g., hardness) of the contact area significantly affect the sensor output and the deformation of the contact object, so the design must be tailored to the application and the hardness of the object. However, with conventional technology, once the contact area is formed, it is difficult to change its shape and material, requiring a separate sensor for each application or object. Furthermore, if the contact area is damaged by a high load, the sensor chip also becomes unusable.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a MEMS sensor in which the contact portion can be easily replaced according to the application and the object. [Means for solving the problem]

[0006] The MEMS sensor according to an embodiment of the present disclosure comprises: a sensor chip sealed with elastic resin; a contact portion provided on the sensor chip; A MEMS sensor comprising: The contact portion is removably fixed to the sensor chip.

[0007] Moreover, the MEMS sensor according to an embodiment of the present disclosure is characterized in that the sensor chip has a microcantilever.

[0008] Furthermore, the MEMS sensor according to an embodiment of the present disclosure is characterized in that the contact portion is removably fixed to the sensor chip by an adhesive.

[0009] Furthermore, the MEMS sensor according to an embodiment of the present disclosure includes a hole defined by the elastic resin on the sensor chip and a protective layer that protects the sensor chip, The contact portion is characterized in that it is removably fixed to the sensor chip by fitting into the hole portion.

[0010] Furthermore, the MEMS sensor according to an embodiment of the present disclosure is characterized in that it includes a base portion on the sensor chip at a position where the contact portion is removably fixed.

[0011] Furthermore, the MEMS sensor according to the embodiment of the present disclosure is characterized in that, when a shear force equal to or greater than a predetermined value is applied to the contact portion, the contact portion comes off the sensor chip. [Effects of the Invention]

[0012] According to the MEMS sensor according to an embodiment of the present disclosure, the contact portion can be easily replaced depending on the application and the object. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a MEMS sensor according to a comparative example. [Figure 2] 1 is a diagram illustrating a schematic configuration of a MEMS sensor according to an embodiment of the present disclosure. [Figure 3] 1 is a diagram showing a schematic configuration of a microcantilever according to an embodiment of the present disclosure. [Figure 4] 10A and 10B are diagrams illustrating a manner in which a contact portion is fixed according to an embodiment of the present disclosure. [Figure 5] FIG. 2 is a diagram illustrating a schematic configuration of a base part according to an embodiment of the present disclosure. [Figure 6] FIG. 10 shows a MEMS sensor with the contacts bonded together. [Figure 7] FIG. 2 is an enlarged cross-sectional view of a base portion and a contact portion. [Figure 8] 1A and 1B are diagrams illustrating a principle of detecting an external force by a MEMS sensor according to an embodiment of the present disclosure. [Figure 9] FIG. 10 is a diagram showing the comparison results of responses to external forces. [Figure 10]10A and 10B are diagrams showing the response of the MEMS sensor according to the present embodiment when a displacement is applied to the contact portion of the sensor in the horizontal direction. [Figure 11] FIG. 10 is a diagram showing a fixing mode in the first modified example. [Figure 12] FIG. 10 is a diagram showing a schematic configuration of a MEMS sensor according to a first modified example. [Figure 13] 10A and 10B are diagrams illustrating responses of the MEMS sensor according to the first modified example when a normal load is applied and when the load is removed. [Figure 14] 10A and 10B are diagrams illustrating responses of the MEMS sensor according to the first modified example when a shear load is applied and when a shear load is removed. [Figure 15] 10A and 10B are diagrams showing a manner in which a contact portion of a MEMS sensor according to a second modified example is fixed. [Figure 16] FIG. 10 is a diagram showing a schematic configuration of a MEMS sensor according to a second modified example. [Figure 17] FIG. 10 is a diagram showing a response of a MEMS sensor according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals indicate the same or equivalent components. As an example of the MEMS sensor of this embodiment, a sensor for tactile measurement (tactile sensor) will be described.

[0015] First, for comparison, configuration examples of MEMS sensors 401, 501, and 601 according to comparative examples will be described with reference to the schematic configuration and photograph of the device shown in FIG.

[0016] As shown in FIG. 1, MEMS sensors 401, 501, and 601 according to the comparative examples include sensor chips 403, 503, and 603, each having a MEMS structure sealed with elastic resin 402, 502, and 602, such as elastomer (e.g., Poly-dimethyl-siloxane (PDMS)), and contact portions 404, 504, and 604 provided on the sensor chips 403, 503, and 603. The contact portions 404, 504, and 604 come into contact with an object, respectively. When an external force acts on the tops of the contact portions 404, 504, and 604, the contact portions 404, 504, and 604 and the elastic resin 402, 502, and 602 deform, and the MEMS structure is simultaneously deformed by the tension caused by the deformation. The deformation of the MEMS structure is electrically measured, and the external force is calculated internally by a computer. Here, PDMS before hardening is used to bond the sensor chips 403, 503, and 603 to the contact parts 404, 504, and 604. After the PDMS hardens, it is integrated with the PDMS sealing the sensor chips 403, 503, and 603 and fixed onto the sensor chips 403, 503, and 603.

[0017] The shapes and materials of the contact portions 404, 504, and 604 vary depending on the application. For example, the contact portion 404 is cylindrical and made of PDMS. The contact portion 504 is hemispherical and made of PDMS. The contact portion 604 is cylindrical and made of acrylic. As described above, in the MEMS sensors 401, 501, and 601 according to the comparative examples, contact portions were formed on the sensor chip according to the application. However, as described above, the contact portions 404, 504, and 604 are fixed on the sensor chips 403 to 603, integrally with the elastic resins 402, 502, and 602 that seal the sensor chips 403 to 603. Therefore, once the contact portions 404, 504, and 604 are formed on the sensor chips 403, 503, and 603, the only way to change to contact portions with a different shape or material is to cut the contact portions 404, 504, and 604. Furthermore, the shear stress generated during cutting can destroy the sensor chips 403, 503, and 603, or cause irregularities in the cut portions, making it difficult to re-adhere and reuse the contact portions 404, 504, and 604. As such, with the technology according to the comparative example, it is difficult to change the contact portion depending on the application or object, and it is necessary to prepare a different MEMS sensor depending on the application or object.

[0018] On the other hand, the MEMS sensor 1 according to an embodiment of the present disclosure is characterized by its flexible replacement of the contact portion, even when the application or target object is different. First, an overview of the MEMS sensor 1 according to this embodiment will be described, followed by details later. The MEMS sensor 1 has a microstructure (MEMS structure) on a silicon substrate and a protruding structure entirely covered with an elastomer (e.g., polydimethylsiloxane (PDMS)). When an external force acts on the top of the elastomer, the entire elastomer deforms, which in turn pulls and deforms the MEMS structure. The deformation of this MEMS structure can be electrically measured and the external force calculated internally by a computer. In this case, the elastomer covering the MEMS structure and the upper protruding structure are manufactured separately and removably bonded together. This allows the sensor characteristics to be changed inexpensively and easily by changing the shape of the upper structure while maintaining the same MEMS structure, which would otherwise be costly to change. Furthermore, by designing the protruding structure to detach when excessive external force is applied, damage to the MEMS structure can be prevented. Below, the details of the MEMS sensor 1 according to an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0019] The configuration of the MEMS sensor 1 according to this embodiment will be described with reference to Fig. 2. Fig. 2(a) is a perspective view of the MEMS sensor 1 according to this embodiment. Fig. 2(b) is a photograph of the MEMS sensor 1 according to this embodiment. The MEMS sensor 1 according to this embodiment includes a sensor chip 3 sealed with elastic resin 2, and a contact portion 4.

[0020] 2, the sensor chip 3 is protected by being sealed with an elastic resin 2. The elastic resin 2 is, for example, an elastomer (for example, Poly-dimethyl-siloxane (PDMS)). In the following description of this embodiment, the elastic resin 2 is assumed to be PDMS.

[0021] The sensor chip 3 is provided on a printed circuit board 5. The sensor chip 3 includes a MEMS structure. In this embodiment, the MEMS structure included in the sensor chip 3 is three microcantilevers (miniature cantilevers) 31 to 33 equipped with strain gauges. The microcantilevers 31 to 33 have an inclined structure for detecting the magnitude and direction of force. The sensor chip 3 is a square with sides of 5 mm. The microcantilevers 31 to 33 are arranged within a circle with a diameter of 1 mm from the center of the sensor chip 3, with their tips facing in a direction rotated 120 degrees.

[0022] Referring to Figure 3, the manufacturing procedure and schematic configuration of microcantilevers 31 to 33 are shown. To manufacture the microcantilevers 31 to 33, a silicon-on-insulator (SOI) wafer consisting of a three-layer structure of a support substrate 311, a BOX layer 312, and an active layer 313 is used. Here, the support substrate 311 is made of Si. The BOX layer 312 is made of SiO2. The active layer 313 is made of Si. As preparation for manufacturing, the SOI wafer is subjected to ultrasonic cleaning with acetone and pre-treatment with dilute hydrofluoric acid to remove the native oxide film.

[0023] First, Si3N4 is deposited on an SOI wafer as insulating layer 314 by LPCVD, NiCr as strain gauge 315, and Au as wiring portion 316 by sputtering, and then these are patterned by photolithography and etching. Next, Cr is deposited by electron beam evaporation as film 317 for tilting the microcantilever, and patterned by lift-off. After that, a microcantilever is formed using the BOX layer 312 as a sacrificial layer by a method of fabricating a hollow structure by selective etching (hereinafter also referred to as sacrificial layer etching).

[0024] After patterning using photolithography, the active layer 313 is etched, leaving the microcantilever shape. To ensure uniform and efficient sacrificial layer etching, multiple holes exposing the BOX layer 312 are formed in the microcantilevers 31-33. Next, to separate the active layer 313, which will become the microcantilevers 31-33, from the support substrate 311, the BOX layer 312 is selectively etched using buffered hydrogen fluoride (BHF). For example, a 20% NH4F product from Stella Chemifa Corporation can be used as the buffered hydrofluoric acid. When the active layer 313 separates from the substrate and becomes hollow, the microcantilevers 31-33 autonomously tilt due to the tensile stress caused by the difference in the linear expansion coefficients of the film 317 (Cr) and the active layer 313 (Si). After the sacrificial layer etching, the sensor chip 3 is washed with pure water, and then ethanol is used to prevent the microcantilevers from sticking to the support substrate 311 due to the surface tension of the pure water. Thereafter, vacuum drying is performed to complete the sensor chip 3.

[0025] The fabricated sensor chip 3 is adhered to the printed circuit board 5 using an epoxy adhesive. As the epoxy adhesive, for example, an ultra-fast epoxy adhesive from Esco Corporation can be used. The sensor chip 3 is electrically connected to the printed circuit board 5 by a wiring connection part 34. The wiring connection part 34 is formed of, for example, a fine gold wire (φ25 μm), and the sensor chip 3 and the printed circuit board 5 are connected by wire bonding.

[0026] Here, the sensor chip 3 is sealed with the above-mentioned elastic resin 2 to protect the microcantilevers 31 to 33 and the wiring connection parts 34. Specifically, PDMS is applied to the sensor chip 3 with a thickness of several tens of μm using a spin coater. As the PDMS, for example, SILPOT184 (Shore A hardness: 50) manufactured by Dow Corning Toray can be used. The PDMS is cured by baking at 90°C for 30 minutes.

[0027] Furthermore, the wiring connection portion 34 is sealed with a protective layer 35 in addition to the elastic resin 2. The protective layer 35 is, for example, a UV-curable resin. The protective layer 35 is formed to prevent disconnection due to contact with the wiring connection portion 34 when the contact portion 4 is installed, and is not an essential component. In this embodiment, the description will be given assuming that the protective layer 35 is provided. The procedure for sealing the wiring connection portion 34 with the protective layer 35 (hereinafter referred to as UV-curable resin) is as follows.

[0028] The printed circuit board 5, to which the sensor chip 3, sealed with elastic resin 2, is attached, is placed in an acrylic container, and the interior of the acrylic container is immersed in UV-curable resin. The thickness of the protective layer 35 can be adjusted by adjusting the amount of UV-curable resin poured into the acrylic container. This prevents the wiring connection 34 from being exposed. Next, a vacuum desiccator is used to degas the UV-curable resin for 30 minutes to remove any air bubbles. After degassing, the UV-curable resin is exposed to ultraviolet light through a photomask. This selectively hardens the UV-curable resin covering the wiring connection 34. By precisely aligning the light-shielding portion of the photomask using a mask alignment device, the microcantilever portion is not hardened, and only the wiring connection 34 is selectively hardened. For example, a M-1S model from Mikasa Corporation can be used as the mask alignment device. Next, the unhardened UV-curable resin is dissolved and removed with acetone, and the printed circuit board 5 is vacuum-dried.

[0029] As shown in FIG. 4 , a contact portion 4 is bonded onto the sensor chip 3 sealed with the elastic resin 2 in the above-described procedure. The contact portion 4 is the portion that comes into contact with the object. The shape and material of the contact portion 4 are determined appropriately depending on the properties and application of the object. The properties of the object include the hardness, flexibility, brittleness, durability, abrasion resistance, etc. of the object. For example, the hardness of the contact portion 4 and the contact area with the object can be adjusted appropriately depending on whether the object is flexible or fragile. For example, the shape of the contact portion 4 may be a hemisphere, a cylinder, an elliptical cylinder, a prism, a triangular pyramid, etc. However, the shape of the contact portion 4 is not limited to these shapes and any protruding shape can be used. The material of the contact portion 4 is, for example, PDMS, acrylic, etc. However, the material of the contact portion 4 is not limited to these shapes and any material can be used. The contact portion 4 limits the contact area with the object and concentrates the load on the sensor chip 3 toward the center.

[0030] Next, a procedure for fixing the contact portion 4 to the sensor chip 3 will be described. In the MEMS sensor 1 according to this embodiment, the contact portion 4 is removably fixed to the sensor chip 3. In this disclosure, "removable" includes being releasable, being detachable, and the like. For example, the contact portion 4 is removably (separably) fixed to the sensor chip 3 by a releasable adhesive 6. As the adhesive 6, for example, the liquid adhesive BBX manufactured by Cemedine Co., Ltd. can be used. Because the contact portion 4 is detachable from the sensor chip 3 in this way, the MEMS sensor 1 according to this embodiment can be used by appropriately replacing the contact portion 4 with a shape or material suited to various applications and targets.

[0031] Here, a base portion 36 may be provided on the sensor chip 3 at a position where the contact portion 4 is fixed. That is, the base portion 36 may be provided in the elastic resin 2 that seals the sensor chip 3 at a position where the contact portion 4 is fixed. FIG. 5 shows a schematic configuration of the base portion 36. As shown in FIG. 5(a), the base portion 36 is a cylindrical member. For example, the diameter and height of the base portion 36 are 2 mm and 1 mm, respectively. As shown in FIG. 5(b), the base portion 36 is a member provided at a position on the sensor chip 3 where the contact portion 4 is to be provided. The base portion 36 is made of PDMS and is bonded to the elastic resin 2 that seals the sensor chip 3 using uncured PDMS. In this way, the bottom surface of the base portion 36 (the surface facing the elastic resin 2) is integrally formed with the elastic resin 2 using the same material. In other words, the base portion 36 is a protruding portion provided in the elastic resin 2 at a position where the contact portion 4 is to be provided. When the sensor chip 3 is provided with a base portion 36, the contact portion 4 is removably (peelably) fixed to the upper surface of the base portion 36 (the surface opposite the surface facing the elastic resin 2) with an adhesive 6. Figure 6 shows the MEMS sensor 1 with the contact portion 4 adhered. The base portion 36 functions as a base portion on which the contact portion 4 is placed. By providing the base portion 36 on the sensor chip 3, it is possible to prevent the fixed position of the contact portion 4 from shifting.

[0032] Figure 7 is an enlarged cross-sectional view of the base portion 36 and the contact portion 4. As shown in Figure 7, the diameters of the base portion 36 and the contact portion 4 are both 2 mm, which is the same. The height of the contact portion 4 is also 2 mm. Therefore, the total height of the contact portion 4 and the base portion 36 is 3 mm. The sizes of the contact portion 4 and the base portion 36 (here, the height and diameter) can be adjusted appropriately depending on the object to be contacted.

[0033] FIG. 8 shows an overview of the principle of external force detection by the sensor chip 3. As shown in FIG. 8, when an external force is applied to the contact portion 4, the microcantilevers 31 to 33 deform. When the external force is applied to the contact portion 4, the deformation of the contact portion 4 causes a change in the amount of deflection of the microcantilevers 31 to 33. The magnitude of the applied force can be estimated by measuring the change in the electrical resistance of the strain gauges 315 on the microcantilevers 31 to 33. As shown in FIGS. 2 and 3, the three microcantilevers 31 to 33 on the sensor chip 3 have an inclined structure and are arranged at different angles. For example, as shown in FIG. 8(a), when a vertical force (vertical load) is applied to the contact portion 4, the PDMS moves horizontally and expands horizontally because it is incompressible. In other words, in this case, the amount of deflection of all the microcantilevers 31 to 33 increases, and the electrical resistance of the strain gauges 315 decreases uniformly. On the other hand, as shown in Figure 8(b), when a shear force (shear load) is applied, the microcantilevers 31-33 each exhibit different movements depending on the direction of the shear load. Similarly, the change in electrical resistance of the strain gauge 315 also exhibits different responses. Therefore, by measuring the sensitivity characteristics of each microcantilever 31-33 to the load in advance, it is possible to estimate the magnitude and direction of the applied force.

[0034] FIG. 9 shows a comparison of the response of the MEMS sensor 1 according to this embodiment to an external force (here, a vertical load) with the MEMS sensor 401 according to the comparative example. In FIG. 9, "PDMS only" indicates the result for the MEMS sensor 401 according to the comparative example. Furthermore, "PDMS (+adhesive)" and "acrylic (+adhesive)" indicate the results for the MEMS sensor 1 according to this embodiment when the contact portion 4 is made of PDMS and acrylic, respectively. As shown in FIG. 9, the MEMS sensor 1 according to this embodiment and the MEMS sensor 401 according to the comparative example obtained substantially the same response. Also, as shown in FIG. 9, substantially the same response was obtained regardless of whether the material of the contact portion 4 was PDMS or acrylic. Note that while the results shown here are for a vertical external force, substantially the same response was also obtained when the external force was a shear force. As such, the MEMS sensor 1 according to this embodiment exhibits linearity, hysteresis, and sensitivity similar to the MEMS sensor 401 according to the comparative example, and can be used as a sensor with sufficiently high accuracy. Here, hysteresis is a phenomenon that occurs when the influence of a previous change remains during the loading and unloading process. The sensitivity here was defined as the rate of change in resistance when the applied normal load reached 1 N and when the applied shear load reached 0.001 N.

[0035] As described above, the MEMS sensor 1 according to this embodiment has the same sensor accuracy as the MEMS sensor of the comparative example. Furthermore, in the MEMS sensor 1 according to this embodiment, the contact portion 4 that receives an external force is removably fixed to the sensor chip 3. Therefore, the MEMS sensor 1 according to this embodiment allows the contact portion to be easily replaced to suit various applications and targets. Therefore, the MEMS sensor 1 according to this embodiment does not require a separate sensor for each application or target, thereby reducing costs and labor. Furthermore, in the MEMS sensor 1 according to this embodiment, even if the contact portion 4 wears or deteriorates due to repeated use, the contact portion 4 can be removed by peeling it off, and a new contact portion 4 can be fixed. In this way, the MEMS sensor 1 can be maintained inexpensively and easily.

[0036] The timing for replacement of the contact portion 4 when it has worn or deteriorated may be determined by visually inspecting the contact portion 4 or by conducting a periodic performance test.

[0037] Furthermore, according to this embodiment, the contact portion 4 is removably fixed to the sensor chip 3, so that when an external force of a predetermined value or greater is applied, the contact portion 4 comes off, preventing damage to the sensor chip 3. In particular, since the microcantilevers 31 to 33 may be damaged by an excessive load, the contact portion 4 comes off, preventing damage to the microcantilevers 31 to 33.

[0038] FIG. 10 shows the response of the MEMS sensor 1 according to this embodiment when horizontal displacement is applied to the contact portion 4. As the displacement increases, the shear load acting on the contact portion 4 increases, and the strain resistance changes accordingly. When the shear load exceeds the adhesive strength of the bond between the contact portion 4 and the sensor chip 3, the adhesive bond 6 peels off, releasing the shear load. The strain resistance then returns to its value before the displacement was applied, and no damage occurs to the sensor chip 3. Note that the magnitude of the external force that causes peeling of the adhesive bond 6 (the above-mentioned predetermined value) can be changed by changing at least one of the size and shape of the contact portion 4. For example, the predetermined value can be changed by changing the size of the contact portion 4 (the diameter and height, if the contact portion 4 is cylindrical). Similarly, the predetermined value can be changed by changing the shape of the contact portion 4, such as a cylindrical shape, a hemispherical shape, an elliptical cylinder shape, a rectangular prism shape, or a triangular pyramid shape. In this way, the predetermined value can be adjusted by changing the size and shape of the contact portion 4. Furthermore, by changing the size and shape of the bottom surface of the contact portion 4 (the surface bonded to the base portion 36), the predetermined external force required to cause peeling of the bonded portion can be changed. For example, if the shape of the contact portion 4 is cylindrical, the diameter of the bottom surface of the contact portion 4 may be smaller than the diameter of the top surface. In other words, the diameter of the bottom surface of the contact portion 4 may be smaller than the diameter of the remaining portions of the contact portion 4. This causes stress concentration at the bottom surface of the contact portion 4, thereby ensuring peeling at the bonded portion. The shape and size of the contact portion 4 and the manner in which stress concentration is caused at the bottom surface of the contact portion 4 are not limited to these, and any method can be used. For example, the contact portion 4 may have a tapered structure from the top to the bottom surface. Alternatively, the contact portion 4 may have a constricted portion, groove, hole, step, or the like at the bottom surface. In other words, by making at least one of the size and shape of the bottom surface of the contact portion 4 different from the other portions of the contact portion 4, stress concentration occurs at the bonded portion, ensuring peeling at the bonded portion.

[0039] It is also possible to prevent damage to the sensor chip 3 when a normal force is applied to the contact portion 4 of the MEMS sensor 1. For example, a retraction mechanism may be provided that retracts the sensor chip 3 when a normal force of a predetermined level or greater is applied. In this way, damage to the sensor chip 3 can be prevented.

[0040] In this embodiment, the MEMS sensor 1 is described as a tactile sensor, but this is not limiting. The MEMS sensor 1 may be a sensor other than a tactile sensor, such as a pressure sensor or a flow sensor. Alternatively, the MEMS sensor 1 may be a proximity sensor. Even in such a case, the configuration according to this embodiment can solve the same problems related to the contact portion between the MEMS sensor 1 and the object.

[0041] In the present embodiment, the sensor chip 3 includes the microcantilevers 31 to 33, but this is not limiting. The sensor chip 3 may include any mechanical component in addition to or instead of the microcantilevers.

[0042] (First Modification) In the present embodiment, the MEMS sensor has been described as including the base portion 36, but this is not limiting. For example, the MEMS sensor may not include the base portion 36, and the contact portion 4 may be removably fixed on the sensor chip 3. A MEMS sensor not including the base portion 36 (a MEMS sensor according to a first modified example) will be described below. FIG. 11 shows the schematic configuration and fixing manner of a MEMS sensor 101 according to a first modified example. As shown in FIG. 11, the MEMS sensor 101 includes a sensor chip 103 sealed in elastic resin 102 and provided on a printed circuit board 105. A wiring connection portion 134 connecting the sensor chip 103 and the printed circuit board 105 is protected by the elastic resin 102 and a protective layer 135. The contact portion 104 is bonded to the flat elastic resin 102 with an adhesive 106. Specifically, the releasable adhesive 106 is applied to the bottom surface of the contact portion 104 (the surface facing the sensor chip 103). The contact portion 104 is adhered onto the elastic resin 102 that covers the sensor chip 103 by a sticky adhesive 106. The MEMS sensor 101 with the contact portion 104 adhered thereto is shown in Fig. 12. The diameter and height of the contact portion 104 are, for example, 2 mm and 3 mm, respectively.

[0043] FIG. 13 shows the response of the MEMS sensor 101 according to the first modification example when a normal load is applied and unloaded. FIG. 14 shows the response of the MEMS sensor 101 according to the first modification example when a shear load is applied and unloaded. As shown in FIGS. 13 and 14 , when no base portion is provided, significant hysteresis is observed when a load is applied and unloaded, particularly when a shear load is applied. This is thought to be due to the adhesive points shifting due to the applied load, demonstrating the importance of providing a base portion in the above-described embodiment. In other words, providing the base portion 36 in the MEMS sensor 1 according to the above-described embodiment can reduce load-related hysteresis. Although load-related hysteresis occurs when the base portion 36 is not provided, the device can be configured with a simpler configuration. For example, sensing may be performed using the MEMS sensor 101 according to the first modification example under conditions where the effect of hysteresis is small or negligible.

[0044] (Second Modification) In the present embodiment, the contact portion 4 is removably fixed to the sensor chip 3 with the adhesive 6, but this is not limiting. For example, the contact portion 4 may be removably fixed to the sensor chip 3 with double-sided tape. Alternatively, the contact portion 4 may be removably fixed to the sensor chip 3 by a different method. Below, a MEMS sensor in which the sensor chip 3 and the contact portion 4 are removably fixed by a different method (a MEMS sensor according to a second modified example) will be described. FIG. 15 shows the schematic configuration and fixing mode of a MEMS sensor 201 according to the second modified example. As shown in FIG. 15, the MEMS sensor 201 includes a sensor chip 203 sealed in elastic resin 202 and provided on a printed circuit board 205. A wiring connection portion 234 connecting the sensor chip 203 and the printed circuit board 205 is protected by the elastic resin 202 and a protective layer 235.

[0045] As shown in FIG. 15 , in the MEMS sensor 201 according to the second modification, the contact portion 204 is detachably fixed to the sensor chip 3 by fitting into a hole 207 defined by the elastic resin 202 and the protective layer 235. In other words, the contact portion 204 is fixed by being fitted into the hole 207. Here, the contact portion 204 and the elastic resin 202 are in contact with each other. Therefore, the contact portion 204 comes out of the hole 207 when pulled with a force greater than a predetermined value or when a shear force greater than a predetermined value is applied. FIG. 16 shows a schematic configuration of the MEMS sensor 201 according to the second modification. As shown in FIG. 16 , the diameters of the contact portion 204 and the hole 207 of the MEMS sensor 201 according to the second modification are the same, both 2.5 mm. Also, as shown in FIG. 16 , the height of the contact portion 204 is 3 mm. Since the contact portion 204 fits into the hole portion 207, the contact portion 204 does not need to be adhered to the sensor chip 3 with the adhesive 6. Alternatively, in order to increase the strength of fixing the contact portion 204, the contact portion 204 may be adhered to the sensor chip 3 with the adhesive 6. Also, a base portion may be provided at the bottom of the hole portion 207. In this case, the contact portion 204 is in contact with or adhered to the base portion.

[0046] Fig. 17 shows the response of the MEMS sensor 201 according to the second modification to a normal force. As shown in Fig. 17, the MEMS sensor 201 according to the second modification also exhibits linearity, hysteresis, and sensitivity similar to those of the MEMS sensor 1 of this embodiment, and can be used as a sensor with sufficiently high accuracy.

[0047] Although the present disclosure has been described based on the drawings and embodiments, it should be noted that those skilled in the art can easily make various modifications and alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included in the scope of the present disclosure. For example, the functions included in each means and each member can be rearranged so as not to cause a logical contradiction. [Explanation of symbols]

[0048] 1, 101, 201, 401, 501, 601 MEMS sensors 2, 102, 202, 402, 502, 602 Elastic resin 3, 103, 403, 503, 603 sensor chip 31, 32, 33 Microcantilevers 311 Support substrate 312 BOX layer 313 Active layer 314 Insulating Layer 315 Strain Gauge 316 Wiring section 317 Membrane 34, 134, 234 Wiring connection 35, 135, 235 protective layer 36 Foundation 4, 104, 204, 404, 504, 604 contact parts 5, 105, 205 printed circuit board 6, 106 Adhesive 207 Hole

Claims

1. a sensor chip sealed with elastic resin; a contact portion provided on the sensor chip; A MEMS sensor comprising: a hole defined by the elastic resin and a protective layer that protects the sensor chip is provided on the sensor chip; the hole is provided on a MEMS structure included in the sensor chip, The contact portion is removably fixed to the sensor chip in the hole portion.

2. 10. The MEMS sensor of claim 1, wherein the sensor chip comprises a microcantilever.

3. A MEMS sensor according to claim 1 or 2, The contact portion is removably fixed to the sensor chip by fitting into the hole portion.

4. 4. The MEMS sensor according to claim 1, The MEMS sensor, wherein the contacts are removably secured to the sensor chip by a sticky adhesive.

5. 5. The MEMS sensor according to claim 1, A MEMS sensor comprising a base portion on the sensor chip at a position where the contact portion is removably fixed.

6. 6. The MEMS sensor according to claim 1, When a shear force equal to or greater than a predetermined value is applied to the contact portion, the contact portion comes off the sensor chip.

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