WO2023120302A1 - Tactile sensor, robot using tactile sensor, medical device, and tactile feedback device - Google Patents

Abstract

A tactile sensor according to the present invention comprises: a base material; a light source unit positioned on the base material; a light reception unit positioned on the base material; and a tactile unit composed of a flexible porous body and positioned on the light source unit and the light reception unit. The flexible porous body has a network-type phase separation structure, and is provided with a three-dimensional mesh-like skeleton and connected pores formed by the skeleton. The size of the pores is 1-100 times larger than the size of the skeleton. The size of the skeleton is 100 nm to 50 μm. The light source unit emits light having a wavelength of 380 nm to 3 μm. The flexible porous body scatters light emitted from the light source unit. The light reception unit receives the scattered light scattered by the flexible porous body. The intensity of the scattered light is gradually reduced as the flexible porous body is compressed.

Description

Tactile sensors, robots, medical devices, and tactile feedback devices using them

The present invention relates to a tactile sensor, a robot using the same, a medical device, and a tactile feedback device.

In the field of robotics, the sense of touch is important in order to achieve human-like movements with robots, and in recent years, the development of tactile sensors has been active (see Patent Document 1, for example).

Patent document 1 includes a substrate, a light-emitting element and a light-receiving element fixed on the substrate, and a tactile part made of a light-transmitting elastic member provided on the substrate so as to cover the light-emitting element and the light-receiving element. A flexible tactile sensor is disclosed. The light-emitting element and the light-receiving element are embedded in the light-transmitting elastic member and are opposed to each other with the light-transmitting elastic member interposed therebetween. Light emitted from the light emitting element is transmitted through a portion of the light-transmissive elastic member between the light emitting element and the light receiving element and is received by the light receiving element. The amount of light received by the light-receiving element changes as the density of the light-transmitting elastic member changes when an external force is applied to the tactile portion. The flexible tactile sensor acquires a change in the amount of light received by the light receiving element.

A pressure detector has been developed in which a light-receiving element receives the scattered/reflected light emitted by the light-emitting element and is covered with urethane foam to block light emission (for example, non-patented See Document 1 and Patent Document 2). According to Non-Patent Document 1 and Patent Document 2, the light emitted by the light-emitting element is scattered/reflected in the light-scattering elastic material (urethane foam), and the light is scattered around the light-emitting portion in the light-scattering elastic material. Construct an intensity distribution. Since the light-receiving element passes a photocurrent correlated to the intensity of light at the location where it is arranged, the photocurrent can be extracted as a signal. By applying pressure to the light-scattering elastic material, the light-scattering elastic material is deformed. When the light-scattering elastic material is deformed, the light intensity distribution changes in the light-scattering elastic material. This changes the intensity of the light at the location where the light receiving element is arranged. Then, changes in light intensity are extracted as pressure information. In particular, as shown in FIG. 1 of Non-Patent Document 1, in such a pressure sensor, the more the light scattering elastic material is compressed, the higher the density becomes, the more the reflected light increases, and the more the light intensity of the light receiving element increases. To increase.

JP 2013-101096 A Patent No. 4868347

However, the tactile sensor of Patent Document 1 has a problem that it is difficult to replace the light-transmitting elastic member because it is necessary to embed the light source and the light receiving section in the tactile section. In addition, since it is necessary to consider the thickness of the light-emitting element and the thickness of the light-receiving element, and it is necessary to secure the optical path length between the light-emitting element and the light-receiving element, the tactile part is given a certain thickness. There is a limit to miniaturization and high density of sensors.

Further, according to the pressure detectors of Non-Patent Document 1 and Patent Document 2, a certain degree of transparency is required on the optical path of the light emitting element, the scattered light/reflected light from the light scattering elastic material, and the light receiving element. , the skeletal structure of the elastic material for light scattering needs to be sparse. If the elastic material for light scattering represented by urethane foam becomes thinner than a certain amount, light leaks, so the detection accuracy decreases, or even detection may not be possible. Therefore, there is a limit to miniaturization due to restrictions on the arrangement of the elements and restrictions on the thickness of the light-scattering elastic material.

In consideration of the above circumstances, an object of the present invention is to provide a tactile sensor whose tactile part can be easily replaced and which can be miniaturized and increased in density, a robot, a medical device, and a tactile feedback device using the same. It is to be.

A tactile sensor of the present invention comprises a base material, a light source positioned on the base, a light receiving part positioned on the base, and a flexible porous body positioned on the light source and the light receiving part. a tactile part, wherein the flexible porous body has a network-type phase separation structure, the flexible porous body comprises a three-dimensional network skeleton and communicating pores formed by the skeleton, and the pores The pore diameter satisfies the range of 1 to 100 times the skeleton diameter of the skeleton, the skeleton diameter satisfies the range of 100 nm to 50 μm, and the light source unit has a wavelength satisfying the range of 380 nm to 3 μm The flexible porous body scatters the light from the light source section, the light receiving section receives the scattered light scattered by the flexible porous body, and the intensity of the scattered light is equal to that of the flexible porous body becomes progressively smaller as is compressed, thereby solving the above problem.
The pore diameter may satisfy a range of 3 to 20 times the skeleton diameter.
The pore diameter may satisfy a range of 5 to 15 times the skeleton diameter.
A porosity of the flexible porous body may range from 60% to 99%.
A porosity of the flexible porous body may range from 85% to 95%.
The flexible porous body includes silicone, urethane resin, acrylic resin, rubber, polystyrene resin, polyester resin, polyvinyl chloride, polyvinylidene chloride, polyamide resin, polyimide resin, cellulose resin, polyolefin resin, aromatic polyether ketone, and It may be selected from the group consisting of epoxy resins.
The light source unit may be selected from the group consisting of a light emitting diode (LED), a laser diode (LD), an organic EL, and an optical fiber.
The light source section may emit light with a wavelength in the range of 400 nm or more and 1.4 μm or less.
The light source section may emit light with a wavelength in the range of 800 nm or more and 1.1 μm or less.
The light receiving unit may be selected from the group consisting of a photoresistor, a phototransistor, a photodiode, a photomultiplier tube, a photon counter, a CCD image sensor, a CMOS image sensor, an NMOS image sensor, and a solar cell.
The direction of the surface from which the light from the light source part is emitted is the same as the direction of the surface of the light receiving part that receives the scattered light, and the tactile part has a surface from which the light is emitted and a surface that receives the light. may be located above.
The base material may be a flexible substrate.
The controller may further include a controller for controlling the operation of the light source and the light receiver, and the controller may include a memory storing data indicating the relationship between the potential and compressibility of the flexible porous body.
The pore diameter may satisfy a range of 100 nm or more and 200 μm or less.
The skeleton diameter may satisfy a range of 1 μm or more and 8 μm or less.
The bulk density of the flexible porous body may satisfy a range of 0.01 g/cm ³ or more and 0.4 g/cm ³ or less.
A robot according to the present invention includes the tactile sensor described above to solve the above problems.
A medical device of the present invention includes the tactile sensor described above, thereby solving the above problems.
A haptic feedback device according to the present invention includes the haptic sensor described above, thereby solving the above problems.

A tactile sensor according to the present invention includes a base material, a light source part and a light receiving part positioned on the base material, a network type phase separation structure positioned on the light source part and the light receiving part, and a three-dimensional mesh shape. and communicating pores formed by the skeleton, and the pore diameter satisfies the range of 1 to 100 times the skeleton diameter (the skeleton diameter satisfies the range of 100 nm to 50 μm). and a haptic portion comprising: The wavelength of the light from the light source is set to satisfy the range of 380 nm or more and 3 μm or less, and the flexible porous body having a specific relationship between the pore diameter and the skeleton diameter generates scattered light based on the skeleton. do. Then, the light-receiving part that receives the scattered light can detect the deformation of the flexible porous body from the change in the intensity of the scattered light. Here, by using the flexible porous body described above, the intensity of the scattered light from the flexible porous body gradually decreases as the flexible porous body is compressed. deformation can be detected with high accuracy.

According to the tactile sensor of the present invention, since it is not necessary to embed the light source part and the light receiving part in the tactile part, the tactile part can be easily replaced and the thickness of the tactile part can be reduced. Therefore, it is possible to miniaturize the tactile sensor. Furthermore, since the distance between the light source section and the light receiving section can be shortened, it is possible to increase the sensor density.

By applying the tactile sensor of the present invention to devices such as inner-ear earphones and packing, pressure can be used to detect whether these devices are correctly worn. Further, by using the tactile sensor according to the present invention, it is possible to provide a robot equipped with human skin sensation, a medical device such as an endoscope capable of palpation, and a tactile feedback device.

Schematic diagram showing a tactile sensor according to the present invention Schematic diagram showing a flexible porous body Diagram showing the mechanism of the tactile sensor of the present invention Another diagram showing the mechanism of the tactile sensor of the present invention Figure showing SEM image of marshmallow gel P1 Figure showing SEM image of marshmallow gel P2 Figure showing SEM image of marshmallow gel P3 The figure which shows the SEM image of the PMMA porous body P4. Figure showing SEM image of melamine foam P5 SEM image of cosmetic cotton P6 Diagram showing the measurement circuits of Examples 1 to 15 A diagram showing test results using a tactile sensor using marshmallow gel P2 of Example 1 A diagram showing test results using a tactile sensor using melamine foam P5 of Example 5 FIG. 10 is a diagram showing test results using a tactile sensor using the PMMA porous body P4 of Example 4. A diagram showing the wavelength dependence of the scattered light intensity at 50% compression by the tactile sensor of Example 16 Schematic showing a robot arm with a gripper Schematic diagram showing an endoscope Schematic diagram showing a game controller Figure showing SEM image of marshmallow gel P7 Figure showing SEM image of marshmallow gel P8

Embodiments of the present invention will be described below with reference to the drawings. In addition, the same number is given to the same element, and the description is omitted.

FIG. 1 is a schematic diagram showing a tactile sensor according to the present invention.
FIG. 2 is a schematic diagram showing a flexible porous body.

The tactile sensor 100 of the present invention includes a base material 110, a light source section 120 positioned on the base material 110, a light receiving section 130 positioned on the base material 110, and a flexible sensor positioned on the light source section 120 and the light receiving section 130. and a tactile part 140 made of a porous body. With such a configuration, the tactile sensor 100 of the present invention can detect deformation of the flexible porous body.

The flexible porous body has a network-type phase separation structure. A network-type phase-separated structure is a structure in which a so-called skeleton phase is phase-separated while maintaining continuity. If a continuous skeleton morphology composed of curved surfaces is observed with an electron microscope, it can be determined that the flexible porous material has a network-type phase separation structure. The network-type phase-separated structure includes a spinodal decomposition-type phase-separated structure, a viscoelastic phase-separated structure, and the like depending on the manufacturing method. Both structures are known to have a skeletal form in which spherical particles are fused and matured. When the flexible porous body has such a network-type separation structure, Mie scattering easily occurs and can be detected with high accuracy.

The flexible porous body of the present invention has communicating pores 210 (Fig. 2) and a three-dimensional network skeleton 220 (Fig. 2), and has flexibility. Pores 210 are formed by a three-dimensional network skeleton 220 . It can also be said that the voids between the skeletons 220 are the pores 210 . As illustrated in FIG. 2, the scaffold 220 is a shape in which particles are continuously connected. Specifically, the pore diameter of the pores 210 in the flexible porous body applied in the present invention satisfies the range of 1 to 100 times the skeleton diameter of the skeleton 220 . Here, the skeleton diameter satisfies the range of 100 nm or more and 50 μm or less. As a result, in the flexible porous body, even when the external stress is removed, the scattered light can change according to the compressive strain.

In the present specification, the term "flexible porous material" refers to a material whose pore volume is reduced by application of an external stress, compressively deformed with a change in density, but returns to its original state when the external stress is removed. The flexible porous body preferably has a Young's modulus of 10 MPa or less, more preferably 1 kPa or more and 100 kPa or less.

In the specification of the present application, the skeleton diameter is the average value of the diameter d (Fig. 2) of 100 circles inscribed in the skeleton 220 in the electron microscope image. The pore diameter is obtained by randomly drawing 20 lines on the electron microscope image and taking the mean value of the length of the section corresponding to the pore 210 in the 20 lines. Note that each line may have a plurality of sections corresponding to the pores 210 . Skeletal diameter and pore diameter are determined by image analysis using ImageJ (ver. 1.52n; open source and public domain image processing software).

The light source unit 120 emits light with a wavelength that satisfies the range of 380 nm or more and 3 μm or less. As a result, the flexible porous body having a specific relationship between the pore diameter and the skeleton diameter described above does not absorb light from the light source section 120 both when an external stress is applied and when the load is removed. Can scatter. The light receiving section 130 receives scattered light scattered by the flexible porous body, and converts the intensity of the scattered light into an electric signal (for example, potential). Here, the light intensity of the scattered light from the flexible porous body gradually decreases as the flexible porous body is compressed. That is, the scattered light intensity is the highest when the flexible porous body is not compressed, and the scattered light intensity decreases depending on the degree of compression of the flexible porous body.

FIG. 3 is a diagram showing the mechanism of the tactile sensor of the present invention.
FIG. 4 is another diagram showing the mechanism of the tactile sensor of the present invention.

Changes in scattered light intensity and potential changes corresponding to states A to C in FIG. 3 are shown in FIGS. 4A and 4B, respectively. When there is no external stress and the haptic part 140 (flexible porous body) is not compressed (state A in FIG. 3), the light from the light source part 120 is scattered by the skeleton of the haptic part 140 and scattered light 410 is generated. The scattered light 410 is received by the light receiving unit 130, and the intensity of the received scattered light 410 is converted into an electric signal (for example, potential). The intensity I _A of the scattered light in this case becomes high (large) and is converted into a small potential V _A .

When an external stress is applied and haptic portion 140 is compressed (state B in FIG. 3), light from light source portion 120 is similarly scattered. However, since the haptic part 140 is compressed, the skeleton becomes dense, and the intensity I _B of the scattered light 410 becomes lower (smaller) than the intensity I _A. The scattered light intensity I _B in this case is converted to a potential V _B greater than the potential V _A .

When more external stress is applied and haptic 140 is further compressed (state C in FIG. 3), light from light source 120 is similarly scattered, except that haptic 140 is further compressed. The skeleton becomes denser and the intensity _IC of the scattered light 410 becomes lower (smaller) than the intensity _IB . The scattered light intensity I _C in this case is converted to a potential V _C greater than the potential V _B .

A change in scattered light intensity caused by a difference in density due to compression of the tactile part 140 is detected as a change in potential. Therefore, it is possible to detect whether or not there was compression, and furthermore, the degree of compression, from the change in potential. Here, for the sake of simplicity, three types of states A to C have been used for explanation, but since the degree of compression can be detected only by the magnitude of the potential, detailed detection is possible without being limited to these three types.

Furthermore, since such changes in scattered light intensity follow density changes due to compression, they can be detected without a time lag. Furthermore, the light receiving section 130 can detect even a slight change in the scattered light intensity and convert it into an electrical signal, so that even a slight distortion of the tactile section 140 can be easily detected.

The mechanism of the present invention will be explained in more detail.
In the present invention, Mie scattering (multiple scattering) in the flexible porous body forming the tactile part 140 is utilized. It is generally known that particles with a size comparable to the wavelength of light undergo strong Mie scattering. Mie scattering is often regarded as a phenomenon that occurs in spherical particles, but the surface and interior of monolithic porous materials prepared by spinodal decomposition-type phase separation and viscoelastic phase separation also exhibit irregularities such as the fusion of spherical particles. Certain skeletal morphologies are prone to Mie scattering. The inventor of the present application thought that the deformation of the porous body could be detected by detecting the intensity of the light (Tyndall phenomenon) returning to the vicinity of the incident light caused by multiple scattering inside the porous body.

Compressing the monolithic porous body increases the volume ratio of the skeleton in the unit space. Since the macroscopic compression of the monolith does not change the diameter of the skeleton composing the porous material, the change in the skeleton volume ratio can be regarded as the density change of the Mie scattering source. As the density of scattering sources increases, the number of times incident light scatters before it reaches the light receiving section also increases. Repeated scattering causes light to attenuate due to interference. By observing this change in light intensity, tactile evaluation (that is, detection of deformation of the porous body) becomes possible.

Here, the difference between the pressure detectors described in Non-Patent Document 1 and Patent Document 2 and the tactile sensor of the present invention will be described. As described above, the pressure detectors described in Non-Patent Document 1 and Patent Document 2 use urethane foam and utilize scattering/reflection within the urethane foam during compression. Specifically, when the urethane skeleton becomes denser due to compression, the number of scattering/reflecting sources occupying a unit space increases, and the scattering/reflectance from the incident point to the nearby detection point increases. Therefore, the more compressed, the higher the detected light intensity. Therefore, it differs from the mechanism of the tactile sensor of the present invention in that it utilizes the improvement in recurrence due to compression. In addition, since urethane foam is not produced by phase separation, it does not have a spinodal decomposition type phase separation structure or a viscoelastic phase separation structure. Therefore, the intensity of scattered light does not decrease when the urethane foam is compressed. Therefore, the pressure detectors described in Non-Patent Document 1 and Patent Document 2 differ from the tactile sensor of the present invention in terms of mechanism and light scattering elastic material employed.

As described above, a flexible porous body having a predetermined ratio of pore diameter to skeleton diameter produces scattered light regardless of whether the external stress is applied or when the external stress is removed. However, from the viewpoint of generating stable scattered light over a wide wavelength range, the external appearance of the flexible porous body is preferably white.

The pore diameter of the pores 210 of the flexible porous body more preferably satisfies the range of 3 to 20 times the skeleton diameter of the skeleton 220, and more preferably satisfies the range of 5 to 15 times. As a result, in the flexible porous body, even when the external stress is removed, the scattered light can change according to the compressive strain.

The pore diameter of the pores 210 of the flexible porous body is preferably in the range of 100 nm or more and 200 μm or less. As a result, in the flexible porous body, even when the external stress is removed, the scattered light can change according to the compressive strain. The pore diameter of the pores 210 is more preferably in the range of 500 nm or more and 100 μm or less, and still more preferably in the range of 1 μm or more and 50 μm or less.

The skeleton diameter of the skeleton 220 of the flexible porous body is more preferably in the range of 300 nm or more and 20 μm or less, still more preferably in the range of 300 nm or more and 10 μm or less, and particularly preferably 1 μm, from the viewpoint of change in scattered light intensity. It is in the range of 8 μm or less.

The porosity of the flexible porous body preferably satisfies the range of 60% or more and 99% or less. As a result, it is possible to detect changes in the intensity of scattered light that is deformed by external stress. The porosity of the flexible porous body more preferably satisfies the range of 75% or more and 99% or less, and further preferably satisfies the range of 85% or more and 95% or less. As used herein, porosity (percentage) is obtained by dividing the bulk density by the true density, multiplying by 100, and then subtracting from 100. The true density is measured by the helium pycnometry method.

The bulk density of the flexible porous body may preferably be in the range of 0.01 g/cm ³ or more and 0.4 g/cm ³ or less. If the bulk density is within this range, the porosity described above can be satisfied. More preferably, the bulk density may range from 0.05 g/cm ³ to 0.3 g/cm ³ .

Although the thickness of the flexible porous body is not limited, it is preferably in the range of 100 µm or more and 10 cm or less. If the thickness is less than 100 μm, the amount of transmitted light increases, which may lower the detection accuracy. The upper limit of the thickness of the flexible porous body is not particularly limited, but if it exceeds 10 cm, the tactile sensor 100 becomes large, which may make handling difficult. More preferably, the thickness of the flexible porous body may be in the range of 500 µm or more and 3 cm or less.

Examples of flexible porous materials that can satisfy the above conditions include silicone, urethane resin, acrylic resin, rubber, polystyrene resin, polyester resin, polyvinyl chloride, polyvinylidene chloride, polyamide resin, and polyimide resin. , cellulose resins, polyolefin resins, aromatic polyether ketones, and epoxy resins.

Examples of silicones include hydrolysis of silicon alkoxides in compositions containing tetraalkoxysilane (TEAS), methylalkoxysilane (MTAS), and dimethyldialkoxysilane (DMDAS), and polycondensation of the hydrolysis products. It is a silicone composition formed by viscoelastic phase separation accompanying the polycondensation reaction of a given silicon alkoxide in an aqueous solution. For such silicones, for example, Gen Hayase, Bulletin of the Chemical Society of Japan, 94[9], 2021, 2210-2215, Gen Hayase et al., J. Am. Mater. Chem. A, 2014, 2, 6525-6531, Gen Hayase et al., ACS Appl. Polym. Mater. 2019, 1, 8, 2077-2082.

For urethane resins, for example, a curing reaction between a polyol having an alkyl side chain and a polyisocyanate compound is performed in an organic solvent to uniformly gel while controlling phase separation, followed by washing and solvent exchange, followed by drying. obtained by

As the acrylic resin, for example, a mixed solution of water and alcohol in which polymethyl methacrylate (PMMA) is dissolved is cooled, phase-separated, washed with a solvent in which a small amount of plasticizer is dissolved, and then dried. . As another acrylic resin, for example, a mixed solution of dimethyl sulfoxide (DMSO) in which polyacrylonitrile (PAN) is dissolved and water may be cooled to phase-separate and impregnated with a plasticizer. For such acrylic resins, see Shinya Yoneda et al., Polymer, 55, 2014, 3212-3216, for example.

The rubber may be natural rubber, or synthetic rubber such as styrene-butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, and fluororubber. may be

The polystyrene resin is not particularly limited as long as it is a polymer mainly composed of styrene and its derivatives.

Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyethylene naphthalate.

Polyvinyl chloride is a polymer mainly composed of vinyl chloride, and may be a homopolymer or a copolymer. Polyvinylidene chloride is, for example, vinylidene.

The polyamide resin may be, for example, nylon, nylon 6, nylon 66, nylon 11, nylon 610, nylon 612, aromatic nylon, aramid, or the like.

A polyimide resin is, for example, a condensation polymer of tetracarboxylic dianhydride and diamine. Cellulose resins include acetate, triacetate, acetate oxide, and the like.

Polyolefin resins are polymers mainly composed of olefins, such as polyethylene, polypropylene, and polybutene.

Aromatic polyetherketones are, for example, polyetheretherketone (PEEK), polyetherketone, polyetherketoneketone, and polyetheretherketoneketone.

Epoxy resins consist of an epoxy compound alone or this and a curing agent. , an alicyclic epoxy resin, and a dicyclopentadiene type epoxy resin.

The pores 210 of the flexible porous body are preferably filled only with gas (air), but they may contain a liquid or an elastomer having a refractive index different from that of the skeleton 220 as long as the deformability is not significantly impaired. good too. This allows use in liquids such as water.

It should be noted that a known manufacturing technique is arbitrarily adopted for the manufacture of the flexible porous body as described above. For example, "A. Surendran, J. Joy, J. Parameswaranpillai, S. Anas, S. Thomas, An overview of viscoelastic phase separation in epoxy based blends. Soft Matter. 16, 3363-3377 (2020)." methods and "Y. Xin, Q. Xiong, Q. Bai, M. Miyamoto, C. Li, Y. Shen, H. Uyama, A hierarchically porous cellulose monolith: A template-free fabricated, morphology-tunable, and easily functionalizable platform. Carbohydr. Polym. 157, 429-437 (2017).” By appropriately changing the materials, it is possible to produce the flexible porous body according to the present invention.

The light source unit 120 more preferably emits a wavelength in the range of 400 nm or more and 1.4 μm or less. Within this range, a light source is readily available, and Mie scattering is likely to occur particularly in the case of a flexible porous material with high light transmittance such as silicone. Light source unit 120 more preferably emits a wavelength in the range of 800 nm or more and 1.1 μm or less.

The light source unit 120 is not limited as long as it emits light with a wavelength that satisfies the above range. selected from the group consisting of With these, light with a wavelength that satisfies the above conditions can be emitted. A light guide plate using an LED, an LD, or the like, or a liquid crystal display can also be used as the light source section 120 .

The light receiving unit 130 is not particularly limited as long as it can receive scattered light and convert the intensity of the scattered light into an electrical signal. The light receiving unit 130 is illustratively selected from the group consisting of a photoresistor, a phototransistor, a photodiode, a photomultiplier tube, a photon counter, a CCD image sensor, a CMOS image sensor, an NMOS image sensor, and a solar cell. All of these can receive light and convert it into electrical signals, and are readily available.

In FIG. 1, the light source unit 120 and the light receiving unit 130 are paired and three pairs are arranged on the substrate 110, but the present invention is not limited to such a configuration. For example, there is one light source unit 120, and many light receiving units 130 may be arranged around it. A photoreflector having both the light source section 120 and the light receiving section 130 may be used. If a photoreflector is used, the tactile sensor 100 can be easily constructed because it is only necessary to place the tactile part 140 on the photoreflector.

According to the tactile sensor 100 of the present invention, preferably, the direction of the surface from which the light from the light source unit 120 is emitted and the direction of the surface of the light receiving unit 130 that receives the scattered light are the same, and the surfaces from which the light is emitted are preferably the same. and the flexible porous body constituting the tactile part 140 is positioned on the light-receiving surface. The direction of the surface from which the light from the light source unit 120 is emitted and the direction of the surface from which the light receiving unit 130 receives scattered light are the same means that the surface from which the light from the light source unit 120 is emitted and the scattered light from the light receiving unit 130 are the same. It can also be said that the light receiving surface is parallel. With such a configuration, not only is it easy to dispose and replace the tactile part 140, but the scattered light scattered by the tactile part 140 out of the light emitted from the light source part 120 returns 180 degrees. Easy to detect in section 130 . In addition, since it is not necessary to embed the light source section 120 and the light receiving section 130 in the tactile section 140, the tactile section 140 can be made thin, enabling miniaturization. However, if the light receiving unit 130 can receive the scattered light from the tactile unit 140, the direction of the surface from which the light from the light source unit 120 is emitted and the direction of the surface from which the light receiving unit 130 receives the scattered light (for example, a configuration in which the light source unit 120 and the light receiving unit 130 are positioned with the tactile unit 140 interposed therebetween) may also be adopted.

The substrate 110 is not particularly limited as long as the light source unit 120, the light receiving unit 130, and the tactile unit 140 can be positioned thereon. A plastic substrate or the like can be applied. For example, if a flexible plastic substrate is adopted as the base material 110, it can be applied to a robot having human-like skin. Moreover, the base material 110 is not limited to a flat plate, and may be curved. If the direction of the surface from which the light from the light source unit 120 is emitted is not the same as the direction of the surface of the light receiving unit 130 that receives the scattered light, the substrate on which the light source unit 120 is installed and the light receiving unit 130 are installed. You may provide separately the base material which carries out.

The tactile sensor 100 of the present invention may preferably further include a control section (not shown) that controls the operations of the light source section 120 and the light receiving section 130 . The control unit includes an arithmetic processing unit such as a CPU (Central Processing Unit) or FPGA (Field-Programmable Gate Array). For example, the control unit (arithmetic processing unit) controls the light source unit 120 to emit light having a predetermined wavelength at a predetermined timing, and controls the light receiving unit 130 in parallel with the light emitted by the light source unit 120. may be controlled so as to convert the intensity of the received scattered light into an electrical signal (for example, potential).

The control unit may further include a memory (storage device) that stores data indicating the relationship between the potential and compressibility of various flexible porous bodies that can constitute the tactile unit 140 . Thereby, the control section can easily calculate the compressibility and the external stress of the flexible porous body based on the electric signal (for example, potential) from the light receiving section 130 .

According to the tactile sensor 100 of the present invention, unlike Patent Document 1, it is not necessary to detect the light transmitted through the flexible porous body from the light source. is unnecessary, and high density is possible. As a result, a tactile sensor capable of multi-point detection can be realized.

FIG. 16 is a schematic diagram showing a robot arm with a gripper.
FIG. 17 is a schematic diagram showing an endoscope.
FIG. 18 is a schematic diagram showing a game controller.

The tactile sensor 100 of the present invention can be applied to a robot gripper 1610 (Fig. 16), medical equipment such as an endoscope (Fig. 17), or tactile feedback devices such as smart phones and game controllers (Fig. 18). Since the tactile sensor 100 of the present invention has delicate sensations similar to those of human skin, if it is applied to the skin of a robot or a gripper, it enables detection similar to that of a human. If applied to the tip of an endoscope, the condition of the affected area can be detected by lightly touching the affected area without the hard body directly touching the affected area, making it easier to confirm lesions. By applying the tactile sensor 100 of the present invention to devices such as inner-ear earphones and packing, it is possible to detect whether these devices are properly worn by pressure.

The present invention will now be described in detail using specific examples, but it should be noted that the present invention is not limited to these examples.

[Flexible porous material]
As flexible porous bodies, silicone monolithic porous bodies with different properties were produced. As shown in Table 1, 1.0 g of a surfactant (CTAC, cetyltrimethylammonium chloride) and urea were added to 5 mM acetic acid and dissolved at room temperature. Next, 3.0 mL of methyltrimethoxysilane (MTMS) and 2.0 mL of dimethyldimethoxysilane (DMDMS) were mixed with this and stirred for 15 minutes to prepare a composition.

The composition is transferred to a PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) sealed container (gel type), heated at 80 ° C. for 12 hours, reacted (gelling and aging), and a viscoelastic phase separation structure is formed. Wet gels with

The resulting wet gel was removed from the mold and washed once with at least 5 times the amount of pure water and twice with industrial alcohol for at least 6 hours. A porous body (sometimes called marshmallow gel) was obtained. Based on the amounts of acetic acid and urea shown in Table 1, the obtained silicone porous bodies are called marshmallow gels P1 to P3.

As a flexible porous body, a PMMA porous body, which is an acrylic resin, was manufactured by viscoelastic phase separation. Specifically, 10 mL of a mixed solvent of 80% ethanol and 20% water (volume ratio) was kept at 80° C., and 0.40 g of PMMA (average molecular weight 350,000, manufactured by Sigma-Aldrich (Merck)) was added while stirring well. Dissolved. After confirming that the PMMA was completely dissolved, the vial containing the sol was allowed to stand still at 20° C. and air-cooled to effect gelation. The obtained wet gel was immersed twice in a sufficient amount of water for 8 hours, washed, and then immersed in an aqueous solution containing 5% glycerin for solvent exchange. Vacuum drying was performed at room temperature to obtain a PMMA porous body P4.

The properties of marshmallow gels P1 to P3, PMMA porous body P4, melamine foam P5 (manufactured by LEC Co., Ltd., S-691), and cosmetic cotton P6 thus obtained were examined. P1 to P6 were observed with a scanning electron microscope (SEM, Miniscope TM3000, manufactured by Hitachi High-Tech Co., Ltd. and FE-SEM, S-4800, manufactured by Hitachi High-Tech Co., Ltd.). Observation results are shown in FIGS.

FIG. 5 is a diagram showing an SEM image of marshmallow gel P1.
FIG. 6 is a diagram showing an SEM image of marshmallow gel P2.
FIG. 7 is a SEM image of marshmallow gel P3.
FIG. 8 is a SEM image of the PMMA porous body P4.
FIG. 9 is a SEM image of melamine foam P5.
FIG. 10 is a SEM image of the cosmetic cotton P6.

5 to 10 show SEM images at various magnifications for each porous body. According to FIGS. 5 to 7, the marshmallow gels P1 to P3 have a viscoelastic phase-separated structure, a three-dimensional network skeleton in which particles containing silicone as a main component are connected, and through holes formed by the skeleton. (pores). Similarly, according to FIG. 8, the PMMA porous material P4 has a viscoelastic phase-separated structure, and has a three-dimensional network skeleton in which acrylic resin particles are linked, and a porous body P4 having through holes formed by the skeleton. was the body. On the other hand, according to FIG. 9, melamine foam P5 also had a three-dimensional network skeleton, but no continuous particulate structure was observed. According to FIG. 10, the cosmetic cotton P6 was fibrous and not a flexible porous body having a particulate skeleton.

The pore diameter, skeleton diameter, porosity and Young's modulus of marshmallow gels P1 to P3, PMMA porous body P4 and melamine foam P5 were measured. The pore diameter and skeleton diameter were calculated by image analysis using Image J according to the method described above for electron images observed with a scanning electron microscope. The Young's modulus was obtained by dividing the compressive stress when compressed at a compressibility of 1 to 2% by the compressibility. These results are shown in Table 2. The porosity (percentage) was obtained by dividing the bulk density obtained by measuring the volume and weight by the true density, multiplying by 100, and then subtracting from 100.

It should be noted that the cosmetic cotton P6 is fibrous, and it was difficult to measure the pore diameter, skeleton diameter, porosity and Young's modulus.

[Examples 1 to 15]
A tactile sensor was manufactured using the marshmallow gels P1 to P3, PMMA porous body P4, melamine foam P5 and cosmetic cotton P6 described above. A photoreflector (manufactured by ON Semiconductor, QRE1113GR) having a light source (LED) and a light receiving portion (Ge phototransistor) is mounted on a base material. MS1 to MS5 adjusted to the thicknesses shown in Fig. 2 were arranged to form tactile sensors of Examples 1 to 15. The LED used was one that emits light with a wavelength of 940 nm and light with a wavelength of 525 nm.

FIG. 11 is a diagram showing measurement circuits of Examples 1 to 15.

The tactile sensors 100 of Examples 1 to 15 were connected to a DC stabilized power supply (PS30V5A01, manufactured by AS ONE), and changes in voltage and stress/strain were measured with a mechanical testing device (EZ-SX, manufactured by Shimadzu Corporation). The results are shown in FIGS. 12-14.

12 is a diagram showing test results using a tactile sensor using marshmallow gel P2 of Example 1. FIG.
13 is a diagram showing test results using a tactile sensor using the melamine foam P5 of Example 5. FIG.
14 is a diagram showing test results using a tactile sensor using the PMMA porous body P4 of Example 4. FIG.

12(A) and 13(A) respectively apply an external stress (50% compression) to each tactile sensor for 10 seconds, then remove the external stress for 10 seconds and let it rest for 10 seconds. Cycles (10 total cycles) are shown. Figures 12B and 13B are plots of stress versus potential in response to this cycle. Figures 12(C) and 13(C) show the compressive strain versus potential in response to this cycle.

According to FIG. 12(B), in the tactile sensor of Example 1 using marshmallow gel, the potential continuously increases in response to the application of the external stress, and the potential continuously increases in response to the removal of the external stress. decreased to Similarly, according to FIG. 12(C), in the tactile sensor of Example 1, the potential continuously increased as the compressive strain increased, and the potential continuously decreased as the compressive strain decreased. . Although not shown, the tactile sensors of Examples 2 to 3 and Examples 7 to 15 also showed similar profiles, although the magnitudes of potentials were slightly different. The reason why hysteresis is observed in FIG. 12B is that the deformation speed of the marshmallow gel when the external stress is applied differs from the deformation speed of the marshmallow gel when the external stress is removed.

On the other hand, according to FIGS. 13(B) and 13(C), the tactile sensor of Example 5 using the melamine foam P5 did not change its compressive strain even when external stress was applied/unloaded. However, the potential change was slight, and it was insufficient for use as a tactile sensor. Although not shown, the tactile sensor of Example 6 using cosmetic cotton P6 also did not cause a change in potential.

The PMMA porous body P4 has a larger Young's modulus than marshmallow gel and melamine foam, but its shape recovery is slow. Therefore, as shown in FIG. 14A, a test was performed for one cycle in which an external stress (10% compression) was applied to the tactile sensor for 30 seconds and then the external stress was removed for 30 seconds. The reason why the external stress did not return to 0% after the unloading in FIG. The test was terminated at this point.

FIG. 14(B) shows the relationship between stress and potential in response to this cycle, and FIG. 14(C) shows the relationship between compressive strain and potential in response to this cycle. .

According to FIG. 14(B), in the tactile sensor of Example 4 using the PMMA porous body P4, the potential continuously increases in response to the application of the external stress, and the potential increases in response to the removal of the external stress. decreased continuously. Similar to FIG. 12(B), hysteresis was observed, but this is because deformation of the PMMA porous body P4 was slow and strain remained even after the stress became zero. Note that the distortion is eliminated over time, so the hysteresis is closed and the original potential is restored. According to FIG. 14(C), in the tactile sensor of Example 4, the potential continuously increased as the compressive strain increased, and the potential continuously decreased as the compressive strain decreased.

[Example 16]
Example 16 produced another tactile sensor using marshmallow gel P2 described above. A halogen light source (Kenko Tokina Co., Ltd., KTX-100E) as a light source and a mini-spectrometer (Hamamatsu Photonics Co., Ltd., C13555MA) as a light receiving unit are connected to the optical fiber tip, respectively, on the substrate with a distance of 5 mm. A tactile sensor of Example 16 was obtained by placing a marshmallow gel P2 (a cylinder with a diameter of 24 mm and a height of 20 mm) thereon. The halogen light source had a wider range than the 350 nm to 830 nm shown in FIG. Using the above-described mechanical testing apparatus, the ratio of the scattered light intensity when the marshmallow gel P2 was compressed by 50% to the scattered light intensity detected by the light receiving unit when the marshmallow gel P2 was not compressed was examined. The results are shown in FIG.

FIG. 15 is a diagram showing the wavelength dependence of the scattered light intensity when the tactile sensor of Example 16 is compressed by 50%.

In FIG. 15, the vertical axis is the percentage of the scattered light intensity ratio at 50% compression to the scattered light intensity at non-compression. According to FIG. 15, when a flexible porous body made of silicone is used as the tactile part, the flexible porous body absorbs incident light with a wavelength of less than 380 nm in its skeleton, and therefore changes in compression are detected by changes in scattered light intensity. could not. This indicates that it is necessary to use a light source section that emits light having a wavelength of 380 nm or more.

According to FIG. 15, it was found that the scattered light intensity ratio was maintained at about 30% in the wavelength range of incident light from 400 nm to 850 nm. Although FIG. 15 shows only a wavelength up to 850 nm, it was confirmed that the scattered light intensity ratio of about 30% was maintained up to a wavelength of 3 μm. From this, it was shown that the tactile sensor of the present invention can use a light source unit that emits light having a wavelength in the range of 380 nm to 3 μm.

As flexible porous bodies, marshmallow gels P7 and P8, which are silicone monolithic porous bodies, were also manufactured.

Marshmallow Gel P7 was manufactured as follows. 3.0 mL of methyltriethoxysilane (MTES) and dimethyldiethoxysilane (DMDES ) was added and stirred for 10 minutes, 1.33 mL of 1 M aqueous ammonia was added, and the mixture was strongly stirred for 1 minute to prepare a composition.

Then, the composition was immediately transferred to an airtight container and allowed to stand at room temperature for 15 minutes to gel, and then aged at 80°C for 1 day to prepare a wet gel.

The resulting wet gel was taken out of the container and immersed and washed for a total of 24 hours or more while exchanging ethanol at 80°C every few hours. Finally, marshmallow gel P7 was obtained by evaporating and drying the wet gel after immersion and washing.

Marshmallow Gel P8 was manufactured as follows. 2.6 mL of methyltrimethoxysilane (MTMS) and 2.6 mL of dimethyldimethoxysilane (DMDMS) were added to a mixed solution of 25 mL of a 5 mM acetic acid aqueous solution, 1.0 g of n-hexadecyltrimethylammonium chloride (CTAC), and 8.0 g of urea. A composition was prepared by adding 4 mL and stirring for 30 minutes. The composition was then transferred to a closed container.

The sealed container was allowed to react (gelling and aging) at 80°C for one day to prepare a wet gel. The resulting wet gel was taken out of the container and immersed and washed for a total of 24 hours or more while exchanging ethanol at 80°C every few hours. Finally, marshmallow gel P8 was obtained by evaporating and drying the wet gel after immersion and washing.

FIG. 19 is a diagram showing an SEM image of marshmallow gel P7, and FIG. 20 is a diagram showing an SEM image of marshmallow gel P8. According to FIGS. 19 and 20, the marshmallow gels P7 and P8 have a viscoelastic phase-separated structure, a three-dimensional network skeleton in which particles containing silicone as a main component are linked, and through-holes formed by the skeleton. (pores).

The pore diameter, skeleton diameter, porosity, Young's modulus and bulk density of marshmallow gels P7 and P8 were measured in the same manner as P1 to P5. These results are shown in Table 4.

As with the tactile sensor of Example 1, the tactile sensors using the marshmallow gels P7 and P8 exhibit potential increased continuously and the potential decreased continuously in response to the removal of the external stress. Further, in the tactile sensors using the marshmallow gels P7 and P8, similarly to the tactile sensor of Example 1, the potential continuously increases as the compressive strain increases, and the potential continuously increases as the compressive strain decreases. A decreasing trend was also observed.

From the above, the light source unit and the light receiving unit are provided on the base material, and the three-dimensional mesh-like skeleton and the communicating pores formed by the skeleton are provided on the light source unit and the light receiving unit, and the pore diameter is the skeleton In a tactile sensor provided with a tactile part made of a flexible porous body satisfying a range of 1 to 100 times, preferably 3 to 20 times the diameter, when emitting light with a wavelength in the range of 380 nm to 3 μm, The flexible porous body scatters the light from the light source, and the light receiving part receives the scattered light scattered by the flexible porous body. rice field.

Because the tactile sensor of the present invention uses scattered light generated by a flexible porous body, even subtle pressure changes can be detected with high accuracy. By applying such a tactile sensor to the surface of a robot, it is possible to provide a robot having human-like movements and sensations. A medical device and a tactile feedback device can be provided by applying such a tactile sensor to the tip of an endoscope.

REFERENCE SIGNS LIST 100 tactile sensor 110 base material 120 light source section 130 light receiving section 140 tactile section 210 pore 220 skeleton 410 scattered light 1610 gripper

Claims (19)

1. a substrate;
   a light source unit located on the base material;
   a light receiving portion positioned on the base material;
   a tactile part positioned on the light source part and the light receiving part and made of a flexible porous body,
   The flexible porous body has a network-type phase separation structure,
   The flexible porous body comprises a three-dimensional network skeleton and communicating pores formed by the skeleton,
   The pore diameter of the pores satisfies the range of 1 to 100 times the skeleton diameter of the skeleton,
   The skeleton diameter satisfies the range of 100 nm or more and 50 μm or less,
   The light source unit emits light with a wavelength that satisfies a range of 380 nm or more and 3 μm or less,
   The flexible porous body scatters light from the light source,
   The light receiving unit receives scattered light scattered by the flexible porous body,
   The tactile sensor, wherein the intensity of the scattered light gradually decreases as the flexible porous body is compressed.
2. The tactile sensor according to claim 1, wherein the pore diameter satisfies a range of 3 to 20 times the skeleton diameter.
3. The tactile sensor according to claim 2, wherein the pore diameter satisfies a range of 5 to 15 times the skeleton diameter.
4. The tactile sensor according to any one of claims 1 to 3, wherein said flexible porous body has a porosity in the range of 60% or more and 99% or less.
5. The tactile sensor according to claim 4, wherein said flexible porous body has a porosity in the range of 85% or more and 95% or less.
6. The flexible porous body includes silicone, urethane resin, acrylic resin, rubber, polystyrene resin, polyester resin, polyvinyl chloride, polyvinylidene chloride, polyamide resin, polyimide resin, cellulose resin, polyolefin resin, aromatic polyether ketone, and The tactile sensor according to any one of claims 1 to 5, which is selected from the group consisting of epoxy resins.
7. The tactile sensor according to any one of claims 1 to 6, wherein the light source unit is selected from the group consisting of light emitting diodes (LED), laser diodes (LD), organic EL, and optical fibers.
8. The tactile sensor according to any one of claims 1 to 7, wherein the light source unit emits light with a wavelength in the range of 400 nm or more and 1.4 µm or less.
9. The tactile sensor according to claim 8, wherein the light source unit emits light with a wavelength in the range of 800 nm or more and 1.1 µm or less.
10. 10. The light receiving unit is selected from the group consisting of a photoresistor, a phototransistor, a photodiode, a photomultiplier tube, a photon counter, a CCD image sensor, a CMOS image sensor, an NMOS image sensor, and a solar cell. The tactile sensor according to any one of 1.
11. the direction of the surface from which the light from the light source unit is emitted is the same as the direction of the surface of the light receiving unit that receives the scattered light;
    The tactile sensor according to any one of claims 1 to 10, wherein the tactile portion is positioned on the light emitting surface and the light receiving surface.
12. The tactile sensor according to any one of claims 1 to 11, wherein the base material is a flexible substrate.
13. Further comprising a control unit for controlling the operation of the light source unit and the light receiving unit,
    13. The tactile sensor according to any one of claims 1 to 12, wherein said control unit comprises a memory storing data indicating the relationship between the potential and compressibility of said flexible porous body.
14. The tactile sensor according to any one of claims 1 to 13, wherein the pore diameter satisfies the range of 100 nm or more and 200 µm or less.
15. The tactile sensor according to any one of claims 1 to 14, wherein the skeleton diameter satisfies a range of 1 µm or more and 8 µm or less.
16. The tactile sensor according to any one of claims 1 to 15, wherein the flexible porous body has a bulk density in the range of 0.01 g/cm ³ to 0.4 g/cm ³ .
17. A robot equipped with the tactile sensor according to any one of claims 1 to 16.
18. A medical device comprising the tactile sensor according to any one of claims 1 to 16.
19. A tactile feedback device comprising the tactile sensor according to any one of claims 1 to 16.

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