An animal-hair-like broadband flexible tactile sensor and array thereof

Abstract

The present application provides a kind of animal whisker imitated broadband flexible tactile sensor, comprising: bionic whisker, bionic skin, upper stress regulating blood sac, piezoelectric sensitive layer, lower stress regulating blood sac and flexible low-frequency force sensitive layer;The bionic whisker has variable cross-section structural characteristics along the length direction, one end is combined with bionic skin in embedded way, the other end is exposed outside bionic skin as external force contact medium layer;The bionic skin has gradient elastic modulus structural characteristics, the lower surface is in contact with upper stress regulating blood sac;The lower surface of the upper stress regulating blood sac is in contact with piezoelectric sensitive layer;The lower surface of the piezoelectric sensitive layer is in contact with the upper surface of lower stress regulating blood sac;The lower surface of the lower stress regulating blood sac is in contact with the upper surface of flexible low-frequency force sensitive layer;The lower surface of the flexible low-frequency force sensitive layer is in contact with the surface of device to be measured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sensors, in particular to a flexible tactile sensor. BACKGROUND

[0002] Tactile sensing technology is one of the key technologies to realize the sensing function of intelligent robots. Intelligent robots rely on tactile sensors distributed in various parts of the body to accurately perceive external information, simulate human tactile perception, sliding perception, thermal perception and other perception functions, and achieve operation tasks. In particular, intelligent robot prosthetic hands want to achieve the easy, natural and dexterous grasping action of human hands, which cannot be achieved without the recognition of various physical information of the contact object by the flexible tactile sensor distributed on the fingertips and palm of the intelligent prosthetic hand, such as contact force, dynamic and static force recognition.

[0003] Flexible tactile sensors are divided into piezoresistive, capacitive, piezoelectric and other types (such as inductive, optical, organic field effect transistor, etc.) according to working principle. However, flexible tactile sensors based on a single sensing mechanism usually have difficulty in achieving simultaneous detection of static and dynamic forces. For example, the response period of flexible tactile sensors based on piezoresistive and piezocapacitive sensing mechanisms is generally tens of milliseconds, which limits their ability to detect vibrations exceeding 10 Hz; on the contrary, flexible tactile sensors based on piezoelectric and triboelectric mechanisms have better high-frequency response capability, but cannot effectively detect static pressure. In view of the problem of how to simultaneously achieve static and dynamic force detection of flexible tactile sensors, the main solutions proposed by domestic and foreign researches are as follows: one is to prepare a composite material with a single sensitive layer by combining sensing mechanisms; the other is to design a composite sensing mechanism with independent sensitive layers by using a laminated structure.

[0004] Flexible tactile sensors of composite material type usually dope dynamic / static force detection sensitive materials in static / dynamic force sensitive materials, such as doping piezoresistive materials such as graphene and metal nanowires in piezoelectric materials, to prepare a single sensitive layer composite material, and then use piezoresistive-piezoelectric effect to realize static and dynamic force detection of flexible tactile sensors. For example, the Chinese University of Hong Kong, Hubei University and Massachusetts Institute of Technology in the United States cooperated to study a kind of pressure sensor based on PbTiO3 piezoelectric nanofiber / graphene composite material, and the experimental results showed that the sensor using the composite material could realize a detection bandwidth of 0-80 Hz. The National Institute of Science and Technology in Ulsan, Korea, and East Asia University in Korea also carried out similar research work, prepared a ferroelectric polymer composite material composed of PVDF and reduced graphene oxide, and prepared a fingerprint-like interlocking microstructure in the thin film, and realized the detection of static and dynamic pressure, with a detection bandwidth of 0-30 Hz.

[0005] The laminated structure type flexible tactile sensor is a sensor based on a single original sensing mechanism, and a sensitive layer of complementary force detection function is stacked, such as a piezoelectric / friction sensitive layer stacked with a piezoresistance / capacitance flexible sensitive material, so as to realize the combination of two sensing mechanisms through the laminated structure. For example, a research team of the University of South Korea adopts a layered structure to prepare a piezoelectric / piezoresistance sensor, and the upper and lower layers are AgNWS / PDMS composite films, which are used for detecting static force, and the middle layer is a ferroelectric doped lithium ZnO / PDMS piezoelectric material, which is used for detecting dynamic signal. A research team of Shanghai Jiaotong University also uses a layered structure design, adopts a PVDF film as a dynamic force sensitive unit, and a graphite / PVDF composite film as a piezoresistance unit for detecting static force, and the experimental results show that the detection bandwidth of the sensor is 0-20 Hz.

[0006] In summary, although the research work at home and abroad has made effective research progress on the static and dynamic force collaborative detection of the flexible tactile sensor, the flexible tactile sensor still faces challenges in realizing the frequency band requirement (0-400 Hz) of human-like tactile perception. SUMMARY

[0007] The application provides a wide-band flexible tactile sensor imitating animal whiskers, and realizes the flexible tactile sensor with wide bandwidth and high sensitivity.

[0008] In order to solve the above technical problems, the application provides a wide-band flexible tactile sensor imitating animal whiskers, which comprises a bionic whisker, a bionic skin, an upper stress adjusting blood sac, a piezoelectric sensitive layer, a lower stress adjusting blood sac and a flexible low-frequency force sensitive layer.

[0009] The bionic whisker has a variable cross-section structure feature along the length direction, one end of which is combined with the bionic skin in an embedded manner, and the other end is exposed outside the bionic skin as an external force contact medium layer.

[0010] The bionic skin has a gradient elastic modulus structure feature, and the lower surface is in contact with the upper stress adjusting blood sac; the lower surface of the upper stress adjusting blood sac is in contact with the piezoelectric sensitive layer.

[0011] The lower surface of the piezoelectric sensitive layer is in contact with the upper surface of the lower stress adjusting blood sac; the lower surface of the lower stress adjusting blood sac is in contact with the upper surface of the flexible low-frequency force sensitive layer; and the lower surface of the flexible low-frequency force sensitive layer is in contact with the surface of a device to be measured.

[0012] In a preferred embodiment, the bionic whisker is a three-dimensional structure.

[0013] In a preferred embodiment, the bionic whisker structure covers at least the surface of the upper stress adjusting blood sac.

[0014] In a preferred embodiment: the upper stress-adjusting blood sac is a three-dimensional structure.

[0015] In a preferred embodiment: the piezoelectric sensitive layer is a one-piece structure with patterned electrodes on the upper and lower surfaces.

[0016] In a preferred embodiment: the flexible low-frequency force sensitive layer is a flexible piezoelectric capacitive sensitive layer or a flexible piezoresistive sensitive layer.

[0017] The application also provides a wide-band flexible tactile sensor array imitating animal whiskers, which is arranged by a plurality of flexible tactile sensors as described above.

[0018] Compared with the prior art, the technical scheme of the application has the following beneficial effects:

[0019] 1. One of the advantages of the application is that the strategy of animal whiskers for dynamic signal sensing is introduced into the design of flexible tactile sensors, and a stress regulation structure composed of bionic whiskers, stress-adjusting blood sacs, and flexible pressure sensitive layers is constructed on the surface of the piezoelectric sensitive layer. This structure amplifies the external force through the lever effect of bionic whiskers-bionic skin, and concentrates the external force on the stress-adjusting blood sacs. The fluid in the stress-adjusting blood sacs is not resistant to pressure, which can pull the piezoelectric sensitive layer to produce transverse deformation, realize stress amplification of the piezoelectric sensitive layer, and improve the dynamic sensitivity of the sensor. It is a method for realizing high-frequency bandwidth expansion of flexible tactile sensors.

[0020] 2. The second advantage of the application is to introduce a laminated structure to realize dynamic and static force detection by combining piezoelectric and piezoresistive sensing mechanisms. Compared with flexible tactile sensors based on a single sensing mechanism, the composite sensing mechanism can realize dynamic and static force detection, and is a method for realizing low-frequency bandwidth expansion of flexible tactile sensors. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram of a flexible tactile sensor unit structure imitating animal whiskers prepared by the application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0023] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom end" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0024] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "provided with", "sleeved / connected", "connected" and the like should be broadly understood, for example, "connected" can be wall-mounted connection, can also be detachable connection, or integral connection, can be mechanical connection, can also be electrical connection, can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication of two elements, and for those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0025] Reference Figure 1 The embodiment provides a piezoelectric flexible tactile sensor, which comprises a bionic whisker 1, a bionic skin 2, an upper stress adjusting blood sac 3, a piezoelectric sensitive layer 4, a lower stress adjusting blood sac 5 and a porous CNTs-PDMS pressure sensitive layer 6.

[0026] The bionic whisker 1 has a variable cross-section structure feature, one end of which is combined with the bionic skin 2 in an embedded manner, and the other end is exposed outside the bionic skin 2 as an external force contact medium layer; the bionic skin 2 has a gradient elastic modulus structure feature, and the lower surface is in contact with the upper stress adjusting blood sac; the lower surface of the upper stress adjusting blood sac 3 is in contact with the piezoelectric sensitive layer 4; the piezoelectric sensitive layer 4 is a one-piece planar structure, and the lower surface is in contact with the upper surface of the lower stress adjusting blood sac 5; the lower surface of the lower stress adjusting blood sac 5 is in contact with the upper surface of the porous CNTs-PDMS pressure sensitive layer 6; and the lower surface of the porous CNTs-PDMS pressure sensitive layer 6 is in contact with the surface of a device to be measured.

[0027] This sensor employs a layered structure combining piezoelectric and piezoresistive sensing mechanisms to achieve coordinated static and dynamic force detection in a flexible tactile sensor. It incorporates the hypersensitive dynamic signal detection strategy of animal whiskers into the design of the flexible tactile sensor. A stress-regulating structure, consisting of a biomimetic whisker 1, an upper stress-regulating blood sac 3, a lower stress-regulating blood sac 5, and a porous CNTs-PDMS pressure-sensitive layer 6, is constructed on the surface of the piezoelectric sensitive layer 4. External forces are amplified through the leverage effect of the biomimetic whisker-biomimetic skin, and the whisker optimizes the force transmission path, guiding dispersed external forces to converge and act on the stress-regulating blood sac. The fluid within the blood sac is not pressure-resistant, causing large deformation of the blood sac, which in turn causes coordinated deformation of the piezoelectric sensitive layer. This achieves coordinated control of the magnitude and direction of stress in the piezoelectric sensitive layer, transforming the out-of-plane normal stress into in-plane normal stress. Therefore, the stress on the sensitive layer is greatly amplified, significantly improving the sensor's dynamic sensitivity and ultimately achieving wide-bandwidth detection performance for the flexible tactile sensor.

[0028] The biomimetic beard 1 is a three-dimensional structure and can be any regular geometric shape. In this embodiment, it is a variable cross-section cone.

[0029] The cross-sectional shape, height, number, arrangement, and embedding depth of the bionic beard 1 structure can be designed and optimized based on the leverage effect of the beard-bionic skin. In this embodiment, the bionic beard 1 has a height of 2mm, a circular cross-sectional shape, and a single beard. The bionic skin 2 has a depth of 0.5mm.

[0030] The bionic beard 1 structure at least covers the surface of the stress-adjusting blood sac unit 3. In this embodiment, the bionic beard 1 acts entirely on the surface of the stress-adjusting blood sac unit 3.

[0031] The upper stress-adjusting blood sac 3 and the lower stress-adjusting blood sac 5 are three-dimensional structures and can be any regular geometric shape; in this embodiment, they are semi-ellipsoids.

[0032] The cross-sectional geometry, size, arrangement, and number of the upper stress-adjusting blood sac 3 and the lower stress-adjusting blood sac 5 can be designed and optimized according to the sensor performance. In this embodiment, the bottom surface of the stress-adjusting blood sac is 5mm, the height is 1.5mm, and the number is 1.

[0033] The piezoelectric sensitive layer 4 has patterned electrodes on its upper and lower surfaces. The geometry, size, arrangement, and number of these electrodes can be designed and optimized according to the sensor performance. In this embodiment, the shape is circular with a diameter of 4 mm, and the number is one.

[0034] The piezoelectric sensitive layer 4 can be a flexible piezoresistive sensitive layer or a flexible piezoresistive sensitive layer. In this embodiment, it is a porous CNTs-PDMS piezoresistive layer.

[0035] The bionic whisker 1, the bionic skin 2, the upper stress adjusting blood sac 3, the piezoelectric sensitive layer 4, the lower stress adjusting blood sac 5 and the porous CNTs-PDMS pressure sensitive layer 6 constitute a wide-bandwidth flexible tactile sensor unit of an animal whisker, and a wide-bandwidth flexible tactile sensor array of an animal whisker can be obtained by designing the number and arrangement mode of the units. In the embodiment, the number of the sensor units is one.

[0036] The above merely describes the preferred embodiments of the present application, but the design concept of the present application is not limited to this. Any person skilled in the art can make non-substantial changes to the present application within the technical range disclosed by the present application, and such changes shall not be regarded as departing from the scope of the present application.

Claims

1. A wideband flexible tactile sensor that mimics animal whiskers, characterized in that: Bionic beard, bionic skin, upper stress-modulating blood sac, piezoelectric sensitive layer, lower stress-modulating blood sac and flexible low-frequency force sensitive layer; The bionic beard has a variable cross-section structure along its length, with one end embedded in the bionic skin and the other end exposed outside the bionic skin as a medium for contact with external forces. The bionic skin has a gradient elastic modulus structure, and its lower surface is in contact with the upper stress-regulating blood sac. The lower surface of the upper stress-adjusting blood sac is in contact with the piezoelectric sensitive layer; The lower surface of the piezoelectric sensitive layer is in contact with the upper surface of the lower stress-adjusting blood sac; The lower surface of the stress-adjusting blood sac is in contact with the upper surface of the flexible low-frequency force-sensitive layer; The lower surface of the flexible low-frequency force-sensitive layer is in contact with the surface of the device under test. The biomimetic beard structure at least covers the surface of the stress-regulating blood sac.

2. The wideband flexible tactile sensor mimicking animal whiskers according to claim 1, characterized in that: The bionic beard has a three-dimensional structure.

3. The wideband flexible tactile sensor mimicking animal whiskers according to claim 1, characterized in that: The stress-adjusting blood sac has a three-dimensional structure.

4. The wideband flexible tactile sensor mimicking animal whiskers according to claim 1, characterized in that: The piezoelectric sensitive layer is a one-piece structure with patterned electrodes on its upper and lower surfaces.

5. The wideband flexible tactile sensor mimicking animal whiskers according to claim 1, characterized in that: The flexible low-frequency force-sensitive layer is either a flexible capacitive sensing layer or a flexible piezoresistive sensing layer.

6. A wide-bandwidth flexible tactile sensor array that mimics animal whiskers, characterized in that: It is composed of a plurality of flexible tactile sensors as described in any one of claims 1-5.

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