Piezoelectric resonant flexible tactile sensor

Abstract

The utility model relates to a piezoelectric resonant flexible tactile sensor, which uses a quartz crystal as a sensor sensing unit, uses a thickness tensile vibration mode of the quartz crystal as a main induction vibration mode, is widely applied to various common load sensors for pressure and the like, and is a high-precision mechanical sensor. When an external force is transmitted to the sensing unit, the working principle is based on the change of the vibration frequency of the resonator caused by the stress, the stress is determined through a fixed stress-frequency relationship, and the function of the sensor is realized. The core of the utility model is that the stress test is realized by using the thickness tensile modal vibration of the quartz crystal plate, a novel flexible tactile sensor is processed and manufactured, the frequency of the novel flexible tactile sensor is about twice that of the existing shear type sensor, and the measuring range is also greatly improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to sensor technical field especially relates to a piezoelectric resonance type flexible touch sensor, and the flexible touch sensor is a kind of element similar to human skin touch, also called electronic skin, can sense environmental temperature, humidity, external force deformation and pressure and other information, with the flexibility of human skin, elastic and can be bent at will, can be covered on any curved surface, has wide application in the field of robot. BACKGROUND

[0002] In recent years, many flexible sensor product development and principles are proposed, including piezoresistive, piezoelectric, capacitive and photoelectric type, further in wearable electronic technology, medical care and human-computer interaction interface have more in-depth research, therefore the demand of miniaturization, integration, wisdom gradually increases, such as self-healing, self-driving and visualization etc., however, traditional electronic skin cannot provide multiple and complex function requirements, especially in the sliding, friction, texture function in the skin surface layer sensing of humanoid robot, need higher precision, sensitivity, response time and other mechanical sensors.Piezo group type mechanical sensor is commonly used in pressure and touch feedback system, but in sensitivity and stability is relatively weak, and the stability affected by environmental temperature and humidity is also lower;Capacitive type mechanical sensor has high sensitivity, fast response and high precision etc., but the cost is high, is susceptible to electromagnetic interference and low range problems, cannot be widely applied. SUMMARY

[0003] The utility model provides a piezoelectric resonance type flexible touch sensor to solve the technical problems, and piezoelectric resonance type chip is designed for flexible touch sensor, and high sensitivity force detection function can be realized.

[0004] The utility model solves the technical problems and adopts the technical scheme that provides a piezoelectric resonance type flexible touch sensor, and the flexible touch sensor is multilayer structure, including the substrate, sensing layer and contact layer that are stacked in sequence, the substrate is provided with connecting layer one between sensing layer, sensing layer is provided with connecting layer two between contact layer, the sensing layer is internally installed with force-sensitive chip, and the upper and lower surfaces of the force-sensitive chip are installed with chip electrode one and chip electrode two respectively, the substrate is provided with substrate electrode one and substrate electrode two, substrate electrode one is connected with chip electrode one, substrate electrode two is connected with chip electrode two, the force-sensitive chip adopts piezoelectric resonance type chip, and the contact layer is provided with contact point structure.

[0005] As a supplement to the technical scheme of the utility model, the contact point structure is single or multiple convex structure, and the contact force is transmitted to the sensing layer by the convex structure.

[0006] As a supplement to the technical scheme of the utility model, the piezoelectric resonance type chip is quartz material or piezoelectric ceramic material or piezoelectric polymer.

[0007] As a supplement to the technical scheme of the utility model, the force sensitive chip is AT cut quartz crystal, and has temperature stability.

[0008] As a supplement to the technical scheme of the utility model, the force sensitive chip is a force sensor using thickness tensile vibration mode method, and pressure is applied in the thickness direction of the quartz crystal plate, and the corresponding thickness tensile vibration mode is excited by the quartz crystal resonator, so that the linear relationship between the thickness direction normal stress and vibration frequency is obtained.

[0009] As a supplement to the technical scheme of the utility model, the connecting layer one and the connecting layer two are adhesive materials or welding materials.

[0010] As a supplement to the technical scheme of the utility model, the chip electrode one and the chip electrode two are both conductive metal materials, and the conductive metal material is gold or silver.

[0011] As a supplement to the technical scheme of the utility model, the base material can be elastic textile, plastic or metal.

[0012] As a supplement to the technical scheme of the utility model, the sensing layer material adopts filling material, and the filling material is plastic or adhesive material.

[0013] As a supplement to the technical scheme of the utility model, the base electrode one is connected with the chip electrode one through the chip wire one, and the base electrode two is connected with the chip electrode two through the chip wire two.

[0014] As a supplement to the technical scheme of the utility model, the multilayer structure of the flexible tactile sensor is processed by coating technology.

[0015] Beneficial effects: the utility model relates to a piezoelectric resonance type flexible touch sensor, and the piezoelectric resonance type chip is used to design the flexible touch sensor, the piezoelectric resonance type chip is preferably the quartz crystal plate of AT cut type, the thickness tensile mode of AT cut quartz crystal plate is used to detect the direction of force, which is consistent with the thickness tensile deformation direction, it is the normal stress perpendicular to the surface of the crystal plate, and high sensitivity force detection function can be realized;Since the surface area of the quartz crystal plate is generally larger, the corresponding stress resultant, that is, the range of the force sensor, is also larger, which makes up the buckling defect of thickness shear, and the thickness tensile vibration can also be excited by the electric field in the thickness direction, which simplifies the processing problem.The frequency of the novel flexible touch sensor is about twice that of the current shear type sensor, and the measurement range is also greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is the structural schematic diagram of the utility model;

[0017] Figure 2 It is the quartz crystal thickness shear vibration modal structure diagram of the utility model;

[0018] Figure 3 It is the three-dimensional view of the quartz crystal thickness shear vibration modal structure of the utility model;

[0019] Figure 4 It is the quartz crystal thickness tensile vibration modal structure diagram of the utility model;

[0020] Figure 5 It is the three-dimensional view of the quartz crystal thickness tensile vibration modal structure of the utility model.

[0021] Illustration: 101, base, 102, sensing layer, 103, contact layer, 104, force-sensitive chip, 105, contact structure, 106, connecting layer one, 107, connecting layer two, 108, chip electrode one, 109, chip electrode two, 110, chip wire one, 111, chip wire two, 112, base electrode one, 113, base electrode two. DETAILED DESCRIPTION

[0022] The utility model will be further described below in combination with specific embodiments. It should be understood that these embodiments are only used to illustrate the utility model and are not used to limit the scope of the utility model. In addition, it should be understood that after reading the content taught by the utility model, those skilled in the art can make various changes or modifications to the utility model, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0023] The embodiment of the utility model relates to a piezoelectric resonance type flexible touch sensor, and the flexible touch sensor is a multilayer structure, and is completed by using coating technology and plating process, such as Figures 1-5As shown, it comprises a substrate 101, a sensing layer 102 and a contact layer 103 which are stacked in sequence, a connecting layer one 106 is arranged between the substrate 101 and the sensing layer 102, a connecting layer two 107 is arranged between the sensing layer 102 and the contact layer 103, a force-sensitive chip 104 is installed inside the sensing layer 102, the upper and lower surfaces of the force-sensitive chip 104 are respectively provided with a chip electrode one 108 and a chip electrode two 109, the substrate 101 is provided with a substrate electrode one 112 and a substrate electrode two 113, the substrate electrode one 112 is connected with the chip electrode one 108, the substrate electrode two 113 is connected with the chip electrode two 109, the force-sensitive chip 104 adopts a piezoelectric resonant chip, the contact layer 103 is directly contacted with external pressure, so as to transmit mechanical energy and generate pressure, deformation and touch functions, and a contact structure 105 is usually made on the surface of the contact layer 103 to feedback to the external unit.

[0024] The substrate 101 is made of a textile or plastic or metal or a composite of the above materials, the connecting layer one 106 is coated on the substrate 101 by means of a doctor blade, after the connecting layer one 106 is dried to produce adhesion, the sensing layer 102 is placed thereon, the sensing layer 102 has completed the assembly of the chip electrode one 108, the chip electrode two 109 and the force-sensitive chip 104, the chip wire one 110 and the chip wire two 111 have been laid out and connected with the substrate electrode one 112 and the substrate electrode two 113, the substrate electrode one 112 is connected with the chip electrode one 108 through the chip wire one 110, the substrate electrode two 113 is connected with the chip electrode two 109 through the chip wire two 111, after the sensing layer 102 is dried, the connecting layer two 107 is coated thereon, the contact layer 103 film with the contact structure 105 is attached thereon, and the main structure is completed after drying.

[0025] As a preferred scheme of the contact structure 105, the contact structure 105 is a single or multiple protruding structure which transmits contact force to the sensing layer 102.

[0026] As an illustration of the force-sensitive chip 104, the piezoelectric resonant chip is made of quartz material or piezoelectric ceramic material or piezoelectric polymer or a composite of the above materials; the force-sensitive chip 104 is preferably an AT-cut quartz crystal which has temperature stability; the force-sensitive chip 104 is a force sensor using a thickness-stretch vibration mode method, pressure is applied in the thickness direction of the quartz crystal plate, a corresponding thickness-stretch vibration mode is excited by a quartz crystal resonator, so as to obtain a linear relationship between the thickness direction normal stress and the vibration frequency.

[0027] The force sensing chip 104 of the flexible tactile sensor preferably uses a quartz piezoelectric resonant crystal, which has a linear relationship between the frequency change and the external stress size when the thickness tensile vibration mode is used, thereby obtaining a force frequency coefficient, expanding the test range, optimizing the linearity, and improving the sensitivity.

[0028] The connecting layer one 106 and the connecting layer two 107 can be adhesive or welding material.

[0029] The chip electrode one 108 and the chip electrode two 109 are both conductive metal materials, which are gold or silver.

[0030] The sensing layer 102 material uses a filling material, such as plastic, adhesive, etc.

[0031] The flexible tactile sensor uses a multi-layer coating technology, such as doctor blade coating, spin coating, etc.

[0032] Regarding the quartz piezoelectric resonant crystal as the force sensing unit 104, the use content is as follows:

[0033] 1. Select the shape of the quartz chip that can be applied to the cut type (common AT cut or other cut type) and process metal electrodes on the upper and lower surfaces. The specific metal material is selected according to the process and industry practice. Note that one electrode can be combined with the force applying structure. After the force applying device and the surface of the quartz crystal are avoided from contacting, the electrode is naturally formed;

[0034] 2. The selected quartz crystal chip can be AT cut or other available cut type. The basic principle is to excite the thickness tensile vibration of the quartz crystal plate, thereby obtaining test data based on the thickness tensile vibration frequency;

[0035] 3. The quartz crystal material used can also be other types of piezoelectric crystals or piezoelectric materials;

[0036] 4. Use the thickness tensile mode to couple with the normal stress and obtain the force frequency relationship;

[0037] 5. According to the sensor structure, select the shape, thickness, layout, etc. of the electrode layer;

[0038] 6. Use the layered structure of the composite material containing piezoelectric material.

[0039] As shown in Figures 2-3 , it is a quartz crystal thickness shear vibration mode structure. The quartz crystal with a thickness of 2b is applied with a lateral force (σ 1 ) in the X1 direction, and the force frequency coefficient in the X2 direction is weak, as shown in Figures 4-5 , it is a quartz crystal thickness tensile vibration mode structure. The lateral force (σ 2) in the X2 direction, the force-frequency coefficient in the X2 direction is strong, the quartz crystal resonator is vibrated in the thickness tensile mode through the thickness electric field, so that the resonator works at a higher vibration frequency, and the stress (sigma 2 ) and the corresponding elastic constant are combined, so that the vibration frequency change is approximately proportional to the stress, and due to the weak coupling of the thickness tensile and width tensile vibration modes, it can be approximately considered that the frequency change of the thickness tensile vibration is determined by the stress, so that a novel force-frequency relationship is obtained, and a novel product design and manufacturing are realized.

[0040] At present, the quartz crystal resonant sensor mainly uses thickness shear vibration, the load is applied in the wave propagation direction, and the stress and the frequency are a hyperbolic relationship, that is, the sensitivity is not fixed, and the effective range is limited. The root cause of this phenomenon can be traced back to the relationship between stress and vibration mode. As the working principle of the sensor, it is best to have a linear relationship between stress and frequency, so that better sensitivity can be guaranteed, and consistent signal processing function can be realized. By observing the thickness vibration mode of the quartz crystal resonator, it is found that the thickness tensile mode is proportional to the stress along the thickness direction, directly affects the thickness tensile vibration, and the stress and the elastic constant along the thickness direction are directly combined, resulting in a nearly linear relationship between the vibration frequency and the stress. The allowable stress along the thickness direction depends on the compressive strength of the quartz crystal material, which is much higher than the buckling limit when acting in the wave propagation direction, so that the stress range is greatly improved. The core of the patent is to use the thickness tensile mode vibration of the quartz crystal plate to realize stress testing, and to process and manufacture a new type of flexible tactile sensor. The frequency of the new flexible tactile sensor is about twice that of the current shear sensor, and the measurement range is also greatly improved.

[0041] The utility model discloses a piezoelectric resonance type way is carried out flexible tactile sensor's design, uses the quartz crystal as sensor sensitive unit, uses the thickness tensile vibration mode of quartz crystal, as the main response vibration mode, the quartz crystal resonant sensor is widely used in various pressure and common load sensor, it is a kind of high-precision mechanical sensor, when external force is transmitted to sensitive unit, working principle is based on the change of resonator vibration frequency caused by stress, determines stress size through fixed stress-frequency relationship, realizes sensor function.

[0042] As a high-precision and high-sensitivity sensor, the quartz crystal resonant sensor utilizes the inverse piezoelectric effect of quartz crystal material to generate high-frequency mechanical vibration of quartz crystal, thereby providing a stable frequency source for signal selection and information detection functions, and can also detect the influence of the acting stress on the frequency. The quartz resonant crystal, commonly known as AT-cut thickness shear mode, has weak coupling with other parasitic modes, and can easily concentrate energy in this mode to achieve high-precision detection function. Since the AT-cut quartz crystal mainly uses thickness deformation to generate frequency change, and the sensor generally acts on the wave propagation direction, that is, the quartz crystal plate plane, the coupling between the measured stress and the working mode is relatively weak, and the detection range and precision will also be affected. However, the thickness tensile mode can interact with the force on the surface of the crystal plate, so the thickness tensile mode of the AT-cut quartz crystal plate can be used to detect the force direction, which is consistent with the thickness tensile deformation direction, that is, the normal stress perpendicular to the surface of the crystal plate, and can realize high-sensitivity force detection function.

[0043] Since the surface area of the crystal plate is generally large, the corresponding stress resultant, that is, the range of the force sensor, is also large, which makes up for the buckling defect of the thickness shear, and the thickness tensile vibration can also be excited by the electric field in the thickness direction, which simplifies the processing problem.

[0044] In the description of the utility model, it is understood that the orientation words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" and the like indicated orientation or position relationship is generally based on the orientation or position relationship shown in the drawing, only for the convenience of describing the utility model and simplifying the description, in the case where no opposite statement is made, these orientation words do not indicate and imply that the indicated device or element must have a particular orientation or be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the protection scope of the utility model;The orientation words "inner, outer" refer to the inner and outer of the contour of each component itself.

[0045] For purposes of the description hereinafter, spatial relations terms, for example, "above", "below", "upper", "lower", and the like, can be used with respect to the device and / or features as shown in the figures. However, it will be understood that spatial terms are used herein for purposes of description only and do not necessarily describe a particular orientation of the device or features in use or operation. For example, a device described as above other devices or structures can thereafter be oriented so that the same are below other devices or structures. Accordingly, the exemplary term "above" can encompass both an orientation of above and below. Devices can be oriented in other ways (rotated 90 degrees, or at other orientations) and the spatially relative terms used herein interpreted accordingly.

[0046] In addition, it should be noted that the use of "first", "second", and the like words of distinction do not connote any meaning of importance, but are used solely to differentiate one element from another, and are used in the context of this application only for the purpose of clarity. Thus, the use of such terms is not intended to connote any specific order, emphasis, or importance of any element over or in relation to another element(s).

[0047] The piezoelectric resonance type flexible tactile sensor provided by the application is described in detail above, the principles and implementation modes of the application are described by using specific examples in this paper, the above example is only used to help understand the method of the application and its core idea; at the same time, for the general technical personnel in the art, according to the idea of the application, the specific implementation mode and the application range will be changed, and the above is described, the content of the specification should not be understood as the limitation of the application.

Claims

1. A piezoelectric resonant flexible tactile sensor, the flexible tactile sensor being a multilayer structure comprising, in order, a substrate (101), a sensing layer (102) and a contact layer (103), characterized in that: The base (101) is provided with a connecting layer one (106) between the base (101) and the sensing layer (102), the sensing layer (102) is provided with a connecting layer two (107) between the sensing layer (102) and the contact layer (103), the force sensing chip (104) is installed in the sensing layer (102), the upper and lower surfaces of the force sensing chip (104) are respectively provided with a chip electrode one (108) and a chip electrode two (109), the base (101) is provided with a base electrode one (112) and a base electrode two (113), the base electrode one (112) is connected with the chip electrode one (108), the base electrode two (113) is connected with the chip electrode two (109), the force sensing chip (104) is a piezoelectric resonance type chip, and the contact layer (103) is provided with a contact structure (105).

2. The piezoelectric resonant flexible tactile sensor according to claim 1, characterized in that: The contact structure (105) is a single or multiple convex structure, and the contact force is transmitted to the sensing layer (102) through the convex structure.

3. The piezoelectric resonant flexible tactile sensor according to claim 1, wherein: The piezoelectric resonance type chip is quartz material or piezoelectric ceramic material or piezoelectric polymer.

4. The piezoelectric resonant flexible tactile sensor according to claim 3, wherein: The force sensing chip (104) is an AT-cut quartz crystal.

5. The piezoelectric resonant flexible tactile sensor according to claim 1, wherein: The connecting layer one (106) and the connecting layer two (107) are adhesive glue or welding material.

6. The piezoelectric resonant flexible tactile sensor according to claim 1, wherein: The chip electrode one (108) and the chip electrode two (109) are both conductive metal materials, and the conductive metal material is gold or silver.

7. The piezoelectric resonant flexible tactile sensor according to claim 1, wherein: The base (101) is a textile or plastic or metal material with elasticity. 8.The piezoelectric resonant flexible tactile sensor according to claim 1, wherein: The sensing layer (102) is filled with plastic or glue material.

9. The piezoelectric resonant flexible tactile sensor according to claim 1, wherein: The base electrode one (112) is connected with the chip electrode one (108) through a chip wire one (110), and the base electrode two (113) is connected with the chip electrode two (109) through a chip wire two (111).

10. The piezoelectric resonant flexible tactile sensor according to claim 1, wherein: The multilayer structure of the flexible tactile sensor is processed by coating technology.

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