JP4876240B2 - Tactile sensor and manufacturing method thereof - Google Patents

Description

  The present invention relates to a tactile sensor and a manufacturing method thereof.

  In order to suitably operate an object with a robot hand, it is necessary to measure various contact states such as a frictional force generated on a contact surface as well as a gripping force. For this reason, a tactile sensor that directly measures these contact states at a contact point with an object is required.

In this regard, Patent Document 1 below discloses a configuration of a contact sensor in which a plurality of strain gauges are embedded in a finger-shaped elastic body and the contact state between the object and the elastic body is detected by the strain gauges. Yes. According to this configuration, when the elastic body is deformed by the contact between the object and the elastic body, the strain gauge is also deformed. Therefore, by obtaining the deformation amount of the strain gauge from the output of the strain gauge, the object and the elastic body The contact state with can be detected.
JP 2000-254884 A

  If you want to measure a small deformation of an elastic body with a strain gauge, it is necessary to affix the strain gauge on a rigid plate, but if the strain gauge is embedded in an elastic body together with a rigid plate, the deformation of the elastic body will be reduced. It will interfere. On the other hand, if a strain gauge is directly embedded in an elastic body without using such a flat plate, the resistance of the strain gauge hardly changes, and a minute deformation of the elastic body cannot be measured. For this reason, it is difficult to measure the minute deformation of the elastic body in any case with the above-described conventional technology.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a tactile sensor capable of suitably measuring a minute deformation occurring at a contact point with an object, and a manufacturing method thereof.

  In order to solve the above-described problems, a tactile sensor according to the present invention includes a structure including a sensitive part supported by a hinge part, a detection part that detects a posture of the sensitive part, and at least the sensitive part of the structural body. And an elastic body that covers the portion.

  According to the present invention, since the sensitive part covered by the elastic body is supported by the hinge part, the deformation of the elastic body is not easily disturbed by the structure, and therefore, the slight deformation that occurs at the contact portion of the elastic body with the object is suitable. Can be measured.

  The sensitive part may be formed in a flat plate shape. If it carries out like this, the microdeformation of an elastic body can be efficiently changed into the posture change of a sensitive part, and the microdeformation which arises in an elastic body can be measured suitably. In addition, among the deformations of the elastic body, the component in the thickness direction of the plate-like sensitive part can be suitably measured.

  The structure may have a cantilever (cantilever) structure. By doing so, it is possible to prevent further slight deformation of the elastic body.

  Further, at least two of the structures may be provided, and the structures may be provided such that the direction of change of the posture of the sensitive unit is different from each other. By doing so, it is possible to measure deformation in a plurality of directions in the elastic body.

  In addition, the structure includes at least two hinge portions, piezoresistors are formed on the surface of each hinge portion, the sensitive portion electrically couples the piezoresistors of each hinge portion, and the detection portion is You may make it detect the sum total of the resistance value of each said hinge part as an attitude | position of the said sensitive part. In this way, by measuring the voltage and current at the end of the piezoresistor formed in the hinge part, the total resistance value of each hinge part can be obtained, and thereby the attitude of the sensitive part can be detected.

  In this case, the hinge portions may have the same shape and be provided in parallel on the same surface. In this way, when the sensitive part moves parallel to the surface on which each hinge part is provided, one hinge part extends and the other hinge part shrinks. For this reason, the total resistance value of each hinge part is unlikely to change, and such a movement of the sensitive part can be hardly detected by the detection part.

  The tactile sensor manufacturing method according to the present invention includes a structure having a sensitive part supported by a hinge part, a detection part for detecting the attitude of the sensitive part, and covering at least the sensitive part of the structure. A method of manufacturing a tactile sensor comprising an elastic body, the step of forming a piezoresistive film on the surface of the hinge portion and the sensitive portion, and the step of forming a material film that is a conductor and a magnetic material on the sensitive portion And a step of applying a magnetic field to the structure, and a step of covering at least the sensitive part of the structure with an elastic body.

  According to the present invention, in the step of applying the magnetic field, the magnetic field and the material film that is a conductor and a magnetic substance act to change the attitude of the sensitive part. And the sensitive part which changed the attitude | position in this way can be covered with an elastic body.

  The step of applying the magnetic field may include a step of forming a solid film at least around the hinge part in a state where a magnetic field is applied to the structure. In this way, when the sensitive part is covered with the elastic body, it is possible to prevent a situation in which the posture of the sensitive part is changed or damaged.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing the overall structure of a tactile sensor according to an embodiment of the present invention. 2 is an enlarged perspective view of the structure 12 provided in the tactile sensor 10 shown in FIG. The sensor substrate 16 that is a two-dimensional array of the structural bodies 12 is embedded in the elastic body 14, whereby the tactile sensor 10 according to the present embodiment is obtained. The sensor substrate 16 including the structure 12 is formed by a so-called MEMS (Micro Electro Mechanical System) technology, and is mainly made of silicon. On the other hand, the elastic body 14 includes, for example, rubber as a main component.

  As shown in FIG. 2, the structure 12 has a cantilever (cantilever) structure extending from the edge of the opening 20 d provided in the sensor substrate 16. This cantilever structure is composed of a plate-like sensitive portion 20c and a pair of hinge portions 20a and 20b having one end connected to the base of the sensitive portion 20c and the other end connected to the edge of the opening 20d. ing. The cantilever structure including the sensitive portion 20 and the hinges 20a and 20b is erected from the surface of the sensor substrate 16 in the figure, and the normal direction of the sensitive surface is substantially parallel to the surface of the sensor substrate 16. The structure 12 provided on the sensor substrate 16 is embedded in the elastic body 14 in a state where the cantilever structure is erected in this manner, and is not erected, that is, the normal direction of the sensitive portion 20 c is on the surface of the sensor substrate 16. What is embedded in the elastic body 14 in a state perpendicular to the elastic body 14 is also included.

  That is, as shown in FIG. 1, in the sensor substrate 16, the structures 12 having the structure shown in FIG. 1 constitute a two-dimensional array. A structure 12Y is formed every three rows of the array with the normal direction of the sensitive portion 20c facing in the Y direction in the figure, and adjacent rows of the sensitive portion 20c in the X direction in the figure. Structures 12X in a state in which the normal direction is directed are formed, and further, structures 12Z in a state in which the normal direction of the sensitive portion 20c is directed in the Z direction in the drawing in the adjacent columns. Here, the structures 12X and 12Y have a cantilever structure in a state of standing up with respect to the sensor substrate 16, and the structure 12Z has a cantilever structure in a state of not standing up with respect to the sensor substrate 16. ing. In FIG. 1, the X and Y directions are perpendicular to each other, and are both parallel to the sensor substrate 16. The Z direction is the normal direction of the sensor substrate 16.

  As will be described later, the structure 12X separately detects and detects the X-direction component of the deformation of the elastic body 14, and the structure 12Y separately detects and detects the Y-direction component of the deformation of the elastic body 14. The body 12Z separates and detects the component in the Z direction of the deformation of the elastic body 14. For this reason, the direction and location of the force applied to the elastic body 14 can be easily obtained by combining these detection outputs.

  Here, the structure 12 will be described in more detail. FIG. 3 is a plan view showing the structure 12 (particularly 12X and 12Y) in a state before the cantilever structure is erected. As shown in the figure, the structure 12 includes a sensitive portion 20c, hinge portions 20a and 20b, and electrodes 20e and 20f, and the sensitive portion 20c is disposed at the center of an opening 20d provided in the sensor substrate 16. It is formed in a very thin rectangular flat plate shape, and a conductive magnetic film is formed on the surface thereof. Both the hinge portions 20a and 20b are formed in the same shape of an extremely thin rectangular flat plate, and a piezoresistive film is formed on the surface thereof. Moreover, each one end is connected with the edge part of the opening 20d, and each other end is connected with one side of the sensitive part 20c, both are formed on the same surface, and both are provided in parallel and spaced apart. The conductive magnetic film of the sensitive part 20c is electrically connected to the piezoresistive films of the hinge parts 20a and 20b. In addition, electrodes 20e and 20f made of the same conductive magnetic film as that of the sensitive portion 20c are provided in a portion where the hinge portions 20a and 20b are connected in the peripheral edge of the opening 20d. The electrode 20e is a hinge. The part 20a and the electrode 20f are electrically connected to the hinge part 20b. For this reason, an electric circuit is formed from the electrode 20e to the conductive magnetic film of the sensitive part 20c through the piezoresistive film of the hinge part 20a, and from there to the electrode 20f through the piezoresistive film of the hinge part 20b. For this reason, the sum of the resistance values of the hinge portions 20a and 20b can be obtained by applying a voltage between the electrodes 20e and 20f and measuring the current value. Since the structure 12 is embedded in the elastic body 14 as described above, the posture of the sensitive portion 20c changes according to the deformation of the elastic body 14. At this time, the amount of bending of the hinge portions 20a and 20b also changes, and the total resistance value of the hinge portions 20a and 20b also changes accordingly. For this reason, the deformation amount of the elastic body 14 can be obtained by measuring the total resistance value of the hinge portions 20a and 20b. In addition, since the part which consists of hinge part 20a, 20b and the sensitive part 20c is formed symmetrically about the straight line which is the same plane as hinge part 20a, 20b and equidistant from both, as it mentions later, hinge part 20a is mentioned. When extending, the hinge portion 20b contracts accordingly, and when the hinge portion 20b extends, the hinge portion 20a contracts accordingly. As a result, even if a force is applied to the sensitive portion 20c in the X positive or negative direction, the total resistance value of the hinge portions 20a and 20b is unlikely to change.

  In addition, the thickness of hinge part 20a, 20b is less than 1/100 of the width | variety of the sensitive part 20c, and is formed by the thickness of 1 micrometer or less. For this reason, it deform | transforms notably in the thickness direction compared with another direction. The hinge portions 20a and 20b made extremely thin with a thickness of 1 μm or less have a wide elastic deformation region and can be greatly deformed without being damaged.

  In addition, a movable region (space region) is formed immediately below the cantilever structure, and the elastic body 14 flows into this region. This spatial region is wider in both length and width (for example, 10 μm or more) than the area of the sensitive portion 20c, for example. Thereby, the posture change of the sensitive part 20c is permitted in all directions.

  A sensor substrate 16 that is a two-dimensional array of the structures 12 is embedded in the elastic body 14. The cantilever structure embedded in the elastic body 14 changes its posture according to the deformation of the elastic body 14. By detecting this change in posture, the deformation of the elastic body 14 can be detected. The elastic body 14 plays a role of protecting the cantilever structure and expanding a detection range of one cantilever structure around the cantilever structure.

Here, a manufacturing method of the touch sensor 10 will be described. 4 to 9 show a longitudinal section of the structure 12 in the manufacturing process of the tactile sensor 10, and FIGS. 4 to 7 show a longitudinal section taken along the line AA 'in FIG. 9 shows a longitudinal section taken along line BB ′ in FIG. 4 to 9, halftone dots indicate impurity layers, hatched lines indicate silicon layers, and halftone dots indicate conductive magnetic films. A white portion sandwiched between the silicon layers represents an oxide film (SiO ₂ ).

  When manufacturing the tactile sensor 10 according to the present embodiment, first, an SOI (Silicon On Insulator) wafer is prepared, and, as shown in FIG. (Dot portion) is formed. Next, the conductive magnetic layer such as Cr / Ni is patterned by sputtering, and other regions are etched by reactive ion etching or the like using the conductive magnetic layer as a mask (see FIG. 5). Thereby, the impurity layer and the silicon layer can be removed from the region where the conductive magnetic film is not formed. Next, the conductive magnetic film formed on the surface of the hinge portion 20a (same for 20b) is selectively etched (see FIG. 6). Thereafter, by reactive ion etching or the like, the opening 20d portion, the sensitive portion 20c, and the back portions of the hinge portions 20a and 20b of the back surface of the sensor substrate 16 are etched, and the oxide film appearing on the portions is further removed by HF. Etching is performed using a gas or the like (see FIG. 7). Thus, the opening 20d is formed in the SOI wafer which is the main material of the sensor substrate 16, and the thin film-like sensitive part 20c is supported by the two thin film hinges 20a and 20b extending from the edge. Obtainable.

  In this embodiment, the magnetic field B is applied from the back surface side to the sensor substrate 16 including the structure 12 formed in this way. Thereby, the conductive magnetic film formed on the sensitive part 20c of each structure 12 and the magnetic field B act, and the sensitive part 20c stands up. At this time, among the structures 12, the structures 12X and 12Y form a conductive magnetic film on the sensitive portion 20c, and the structure 12Z does not form a conductive magnetic film on the sensitive portion 20c. ing. For this reason, the sensitive part 20c stands only for the structures 12X and 12Y, and the sensitive part 20c does not stand for the structure 12Z. In the present embodiment, a solid film such as parylene C is deposited in a state where the magnetic field B is applied to the sensor substrate 16 and the sensitive portions 20c of the structures 12 are selectively raised. Thereby, the posture of the sensitive part 20c is maintained and the structure 12 is protected. If an elastic material having high fluidity (low viscosity) is allowed to flow in over a long period of time, the step of depositing this solid film is not necessary. Thereafter, a liquid elastic material is poured onto the sensor substrate 16 so that the entire sensor substrate 16 is covered with the elastic body 14 (see FIG. 9).

  According to the present embodiment, since the sensitive portion 29c covered by the elastic body 14 is supported by the hinge portions 20a and 20b, the deformation of the elastic body 14 is not easily disturbed by the structural body 12, and therefore the object in the elastic body 12 and It is possible to suitably measure the minute deformation generated in the contact portion.

  Further, the sensitive portion 20c is formed in a flat plate shape, and the sensitive portion 20c is provided with the hinge portions 20a and 20b so as to be remarkably easily tilted in the thickness direction. The components in the thickness direction can be separated and detected.

  Further, since the hinge portions 20a and 20b have the same shape and are formed on the same surface, when a force is applied in the lateral direction with respect to the sensitive portion 20c, one hinge portion 20 extends and the other hinge portion 20 will shrink. For this reason, the sum of the resistance values of the hinge portions 20a and 20b is not changed, and it is possible to prevent such a force from affecting the detection output.

In order to demonstrate the effectiveness of this embodiment, a 2 × 2 two-dimensional array of piezoresistive cantilever structures of the dimensions shown in FIG. 10 is created and embedded in an elastic body to obtain a surface area of 19 × 19 mm ² , A tactile sensor having a thickness of 2 mm was prepared. When an array of piezoresistive cantilevers was embedded in the elastic body, a Parylene C layer was deposited on the entire surface of the array by about 1 μm. As the elastic body covering the array, PDMS (Poly Dimethyl Siloxane) in which a coagulant having a relatively high rigidity and rubber were mixed at a volume ratio of 1: 5 was used.

  In order to facilitate data measurement, the array was bonded onto a copper substrate and wired to a circuit formed on the copper substrate. In the experiment, various measurements were performed by connecting a semiconductor parameter analyzer to this circuit.

  Specifically, first, a shear stress in the range of 0.7 to 6.6 kPa was applied to the elastic body surface. When applying a shear stress, a glass substrate was bonded so as to cover the surface of the elastic body, a thin wire was fixed to the glass substrate, and the elastic body surface was deformed by pulling the wire. The wire was initially loaded with a weight of 0.2 N to prevent it from loosening during the experiment.

  Furthermore, a pressure of 0 to 5.5 kPa was applied to the elastic body surface. When applying pressure, the surface of the elastic body is covered with a glass substrate, an acrylic square column is placed on the glass substrate, and a weight is placed on the top of the acrylic square column to uniformly apply the elastic body surface. It was decided to press.

  FIG. 11 shows the total change rate of the resistance value of the hinge portion when a force is applied in the X direction, the Y direction, and the Z direction in FIG. In the figure (a), the black triangle shows the case where shear stress is applied in the X positive direction, the black circle shows the case where shear stress is applied in the X negative direction, and the black triangle shears in the Y positive direction. A case where stress is applied is shown, and a cross indicates a case where shear stress is applied in the negative Y direction. Further, the dotted line shows an approximate curve of the sensor response to the shear stress in the X positive direction, and the solid line shows an approximate curve of the sensor response to the shear stress in the X negative direction. Further, in FIG. 4B, the x mark indicates a case where pressure is applied in the Z direction.

As shown in FIG. 6A, the linearity of the determination coefficient R ² = 0.983 is shown for the shear stress in the X direction, and the resistance value change rate for the shear stress in the same direction is Δr / r = A response of 1.35 × 10 −3 × τ was shown. However, Δr / r is the rate of change of the resistance value with respect to the initial resistance value of the sensor, and τ [kPa] is the magnitude of the stress applied to the tactile sensor.

  Also, FIGS. 9A and 9B show that the responses in the Y direction and the Z direction are very low compared to the response in the X direction to the shear stress in the X direction of the tactile sensor. Therefore, it can be seen that the tactile sensor according to the present embodiment can separately detect any component of the force applied to the elastic body surface.

1 is a diagram illustrating a schematic overall configuration of a tactile sensor according to an embodiment of the present invention. It is an expansion perspective view of the structure contained in a tactile sensor. It is a top view of the structure in the middle of manufacture. It is a longitudinal cross-sectional view which shows the manufacturing process of a tactile sensor. It is a longitudinal cross-sectional view which shows the manufacturing process of a tactile sensor. It is a longitudinal cross-sectional view which shows the manufacturing process of a tactile sensor. It is a longitudinal cross-sectional view which shows the manufacturing process of a tactile sensor. It is a longitudinal cross-sectional view which shows the manufacturing process of a tactile sensor. It is a longitudinal cross-sectional view which shows the manufacturing process of a tactile sensor. It is a figure which shows the dimension of the structure which concerns on an Example. It is a figure which shows the change rate of the sum total of the resistance value of a hinge part when the force of a multi-directional is applied to the sensor surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tactile sensor, 12 Structure, 14 Elastic body, 16 Sensor board | substrate, 20a, 20b Hinge part, 20c Sensing part, 20d Opening, 20e, 20f Electrode.

Claims (11)

A structure including a sensitive portion supported in a standing state from the surface of the substrate by a hinge portion;
A detection unit for detecting the attitude of the sensitive unit;
An elastic body covering at least the sensitive part of the structure;
With
A material film that is a magnetic material is formed on the sensitive part,
A tactile sensor characterized by that. The tactile sensor according to claim 1,
The sensitive part is formed in a flat plate shape,
A tactile sensor characterized by that. The tactile sensor according to claim 1 or 2,
The structure has a cantilever structure;
A tactile sensor characterized by that. The tactile sensor according to any one of claims 1 to 3,
Comprising at least two of said structures,
Each structure is provided such that the direction of change of the posture of the sensitive part is different from each other.
A tactile sensor characterized by that. The tactile sensor according to any one of claims 1 to 4 ,
The structure includes at least two hinge portions,
Piezoresistors are formed on the surface of each hinge part,
The detection unit detects the total resistance value of each hinge unit as the posture of the sensitive unit;
A tactile sensor characterized by that. The tactile sensor according to claim 5 ,
The hinge portions have the same shape and are provided in parallel on the same surface.
A tactile sensor characterized by that. A structure including a sensitive part supported by a hinge part;
A detection unit for detecting the attitude of the sensitive unit;
An elastic body covering at least the sensitive part of the structure;
A tactile sensor manufacturing method comprising:
Forming a piezoresistive film on the surface of the hinge part and the sensitive part;
Forming a magnetic material film on the sensitive part;
Applying a magnetic field to the structure;
Covering at least the sensitive part of the structure with an elastic body;
A method of manufacturing a tactile sensor, comprising: In the manufacturing method of the tactile sensor according to claim 7 ,
The step of applying the magnetic field includes a step of forming a solid film at least around the hinge part in a state where a magnetic field is applied to the structure.
A method for manufacturing a tactile sensor. A substrate comprising at least three structures including a first structure, a second structure, and a third structure;
The first structure having a cantilever structure, comprising a flat plate-like sensitive part supported in a state of being raised from the substrate surface by a hinge part;
The second structure having a cantilever structure, comprising a flat plate-like sensitive portion supported in a standing state from the substrate surface by a hinge portion;
The third structure including a flat plate-like sensitive portion supported in parallel with the substrate surface by a hinge portion;
A detection unit for detecting the posture of each of the sensitive units;
An elastic body covering at least each of the sensitive parts;
With
An opening formed in the substrate is formed on the side of the sensitive portion of the third structure opposite to the direction in which the sensitive portion of the first structure stands.
The normal direction of each sensitive part is different from each other;
Tactile sensor characterized by The opening penetrates the substrate;
The tactile sensor according to claim 9 . In the tactile sensor according to claim 9 or claim 1 0,
A material film that is a magnetic material is formed on each sensitive part of the first structure and the second structure,
The material film is not formed on the sensitive part of the third structure;
Tactile sensor characterized by

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