CN212320964U - Flexible touch sensor array - Google Patents
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- CN212320964U CN212320964U CN202020862744.5U CN202020862744U CN212320964U CN 212320964 U CN212320964 U CN 212320964U CN 202020862744 U CN202020862744 U CN 202020862744U CN 212320964 U CN212320964 U CN 212320964U
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Abstract
The utility model discloses a flexible touch sensor array, which comprises a flexible substrate and a touch sensor array; the touch sensing array comprises N multiplied by M touch sensing units and an interconnection network; the touch sensing unit is a grid-shaped metal foil wrapped and packaged by conformal polymer, and an in-situ hard micro-column array is integrated on each grid-shaped metal foil; the interconnection line network comprises N row lines and M column lines which are vertically crossed, the row lines and the column lines are insulated by crossed insulating pads at the crossed points, and the row lines and the column lines are wrapped and encapsulated by conformal polymer; the flexible substrate is bonded to the tactile sensing array as a unitary body. The utility model discloses according to the mechanism that the resistance pressurized of metal forming changes, constructed the structure of normal position stereoplasm microcolumn extrusion bars form metal forming to use this to combine interconnection line network to construct novel touch sensor array for touch sensing unit, have advantages such as high stability, high sensitivity, low hysteresis, high integration.
Description
Technical Field
The utility model relates to a tactile sensor field, concretely relates to flexible tactile sensor array.
Background
With the continuous progress of material science and manufacturing technology, the society and the industry have put forward new requirements on the functionality, portability, comfort and the like of various electronic devices, and the flexibility becomes an important development direction of new electronic devices. Compared with the traditional rigid electronic device, the flexible deformable flexible electronic device has the important characteristics of flexibility, elasticity and the capability of bearing any deformation, and has wide application prospect in the fields of medical assistance, wearable health monitoring, human-computer interaction and the like.
The flexible touch sensor can give the robot hand the touch like a human hand, and is a core device for realizing intelligent sensing and human-computer interaction of the robot. The sensor can convert the tactile signals into electric signals and can realize the rapid and accurate conduction of tactile information. If a plurality of tactile sensor units are integrated on a flexible substrate, an N x M flexible tactile sensor array can be formed. The array is connected into a whole through interconnection lines, and the change of the contact pressure of multiple points in a certain area can be measured simultaneously through external circuit control, so that the array has great application potential in the fields of medicine, industry, entertainment and the like. Flexible tactile sensors can be largely classified into resistive, capacitive, and piezoelectric based on the sensing mechanism. The working principle of the resistive touch sensor can be summarized as follows: the external contact pressure stimulation causes the resistance value of the sensor to change, and the output current or voltage to change, so that the magnitude of the contact pressure is fed back.
The technical core of the resistance-type flexible touch sensor is to construct a resistance value variable system sensitive to pressure, and the current methods are as follows: 1) the flexible pressure-sensitive conductive material is used as a sensor sensitive unit: the flexible pressure-sensitive conductive material is prepared by taking powdered or granular conductive substances such as carbon black, carbon nano tubes or graphene and the like as conductive substances and doping and curing the conductive substances with silicon rubber, hydrogel and the like, so that a flexible and stretchable pressure-sensitive conductive composite material is formed. The distance between the internal conductive particles is changed under the action of pressure, so that the resistance is changed; 2) variable contact resistance as sensitive unit: the contact resistance can be generated by conducting the upper electrode material and the lower electrode material with the surface microstructures in a contact mode, different contact states can be generated under the action of different pressures, and therefore different contact resistances can be achieved, and the output electric signals can be changed.
The existing resistance-type flexible touch sensor adopting flexible pressure-sensitive conductive materials as a sensor sensing unit can realize distributed pressure measurement, but has obvious defects in the aspects of sensitivity, hysteresis, integration level and the like; the resistive flexible tactile sensor using the variable contact resistance as the sensing unit has a bottleneck in measuring range and integration.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a novel flexible tactile sensor array of resistance-type of high stability, high sensitivity, low hysteresis, high integration degree.
A flexible tactile sensor array comprising a flexible substrate and a tactile sensing array comprising nxm tactile sensing units and a network of interconnecting lines connecting each tactile sensing unit;
the tactile sensing unit is a grid-shaped metal foil wrapped and encapsulated by conformal polymer, and a hard micro-column array is integrated on the grid-shaped metal foil;
the interconnection line network comprises N row lines and M column lines which are vertically crossed, crossed insulating pads are arranged at the crossed points of the row lines and the column lines, and the row lines and the column lines are wrapped and packaged by conformal polymer; the touch sensing array is bonded on the flexible substrate.
The utility model discloses in, flexible basement is a thin layer basement that has a gentle elastic silicon rubber class one kind, and N strip column rule and M strip line are perpendicular alternately to constitute interconnection network, but do the insulating treatment at the crosspoint and make the column rule line contactless not communicate. The touch sensing unit is arranged near the intersection point, one end of the touch sensing unit is connected with the row line, and the other end of the touch sensing unit is connected with the column line. The N multiplied by M touch sensing units form an interconnected touch sensing array through a common row line and column line network.
After the flexible substrate is bonded with the touch sensing array, depending on the flexibility of the substrate, when contact pressure acts on the touch sensing unit, the pressure is amplified by the hard micro-pillars and simultaneously extrudes the metal foil below the touch sensing unit through the hard micro-pillars, and the metal foil is stretched and bent along with the concave-down of the flexible substrate, so that the resistance of the metal foil is changed. When the contact pressure is released, the substrate springs back rapidly due to the elasticity of the flexible substrate, and the shape and resistance of the metal foil are restored. Therefore, in the process of applying and releasing the contact pressure, the resistance of the touch sensing unit can make quick response through the extrusion of the hard micro-column and the concave deformation and quick rebound of the flexible substrate, so that the output electric signal is changed, and the function of sensing the pressure is realized.
The N multiplied by M touch sensing units work simultaneously without influencing each other by scanning an interconnection network formed by N row lines and M column lines through external equipment, and independently sense pressure signals, so that the touch sensor array realizes the function of measuring distributed pressure in real time at multiple points.
The utility model discloses according to the mechanism that the resistance pressurized of metal forming changes, constructed the structure of stereoplasm microcolumn extrusion bars form metal forming to use this to combine interconnection line network to construct novel touch sensor array for touch sensing unit, obtain a novel resistance-type flexible touch sensor array that collects advantages such as high stability, high sensitivity, low hysteresis, high integration degree in an organic whole.
The flexible substrate is preferably a thin layer of PDMS (polydimethylsiloxane) with a thickness of 200 microns, and other flexible and elastic materials such as silicone rubber, hydrogel, dielectric elastomer and the like can be selected to support the touch sensing array, improve the concave deformation space and realize the rapid rebound deformation.
The grid-shaped metal foil is preferably in a rectangular wave grid shape, can also be designed into a linear grid shape or a wave grid shape, the grid width is preferably 20 micrometers, and the grid spacing is preferably 80 micrometers.
The grid-shaped metal foil is formed by a single layer or multiple layers of metal wrapped and encapsulated by conformal polymer, the thickness of each layer of metal is 5 nanometers-100 micrometers, and the thickness of the polymer wrapping is 2 micrometers-200 micrometers.
Preferably, the metal is chromium-gold double-layer metal, the thickness of chromium is 5 nanometers, and the thickness of gold is 100 nanometers.
Preferably, the polymer wrap is made of PI (polyimide) with a thickness of 5 μm, and may be a poly-terephthalic polymer.
In the hard micro-column array, the hard micro-columns are cuboids, cylinders or cones, preferably cuboids, the size is preferably 20 × 35 micrometers, preferably a light-cured resin is used as a material, and a light-cured polymer or a photoresist can be selected.
Preferably, the cross insulating pad is 1-5 micron thick PI (polyimide).
The utility model discloses a flexible touch sensor array adopts following step to prepare:
(1) preparing a flexible substrate with a specific thickness on a silicon wafer by spin coating and thermosetting by adopting a PDMS liquid prepolymer;
(2) preparing a touch sensing array consisting of touch sensing units and an interconnection line network by adopting a micro-nano manufacturing technology;
(3) and transferring and bonding the touch sensor array to a flexible substrate by adopting a water-soluble transfer printing technology to finally obtain the resistance-type flexible touch sensor array.
In the step (1), the spin coating can obtain flexible substrates with different thicknesses by controlling the rotating speed and time, and can also prepare flexible substrates with specific thicknesses by using a mold.
In the step (2), the micro-nano manufacturing technology comprises a photoetching development technology, a metal coating technology and a polymer dry etching technology.
The specific steps of the step (2) are as follows:
(2-1) spin-coating the PI liquid prepolymer on a silicon wafer and thermally curing to prepare a PI bottom layer;
(2-2) after photoetching, developing, metal coating and metal stripping are carried out on the PI bottom layer, a rectangular wave type grid-shaped metal foil and an interconnection line network are prepared on the PI bottom layer, and in the process, the cross point of the interconnection line network is subjected to insulation treatment;
(2-3) spin-coating the PI liquid prepolymer on the silicon wafer, performing thermocuring to form a PI packaging layer, and performing dry etching on PI to enable the PI packaging layer to be conformal with the rectangular-wave grid-shaped metal foil and the interconnection line network, so that a sandwich structure is formed;
(2-4) preparing a hard microcolumn on the sandwich structure by using a photosensitive epoxy resin prepolymer through a photoetching technology, and then completing the preparation of the touch sensing array;
and (2-5) releasing the touch sensing array from the silicon wafer by adopting a chemical reagent soaking mode.
The specific steps of the step (3) are as follows:
(3-1) picking up the released tactile sensing array flat using a water-soluble adhesive tape, the array having one side completely adhered to the tape and the other side exposed, depositing a thin layer of chromium and a thin layer of silica on the exposed side;
(3-2) after the flexible substrate is placed in a plasma cleaning machine and treated by oxygen, the water-soluble adhesive tape adhered with the touch sensor array and the flexible substrate are quickly bonded into a whole by hot pressing, and then the flexible substrate is placed in water to completely dissolve the water-soluble adhesive tape, so that the flexible touch sensor array is obtained.
Compared with the prior art, the utility model discloses following beneficial effect has:
1. the flexible touch sensor array of the utility model can integrate N multiplied by M touch sensing units, each unit independently senses pressure signals, thereby realizing the function of multipoint real-time pressure distribution measurement, having ultrahigh sensitivity and sensing extremely slight pressure;
2. the hard microcolumn design of the resistance-type flexible touch sensor array not only improves the sensitivity, but also ensures the array integration level;
3. the resistance-type flexible touch sensor array has high stability and long service life due to the adoption of the metal material and the micro-nano manufacturing technology;
4. the utility model discloses when the flexible tactile sensor array of resistance-type was prepared, preparation method is simple, the preparation cost is low, and the integrated level is high and wiring and pin are few.
Drawings
Fig. 1 is a general schematic diagram of a resistive flexible tactile sensor array according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a haptic unit according to an embodiment of the present invention;
fig. 3 is a circuit diagram of an interconnection network according to an embodiment of the present invention;
fig. 4 is an enlarged schematic diagram of a tactile sensor unit according to an embodiment of the present invention.
In the figure: 01-flexible substrate, 02-touch sensing array, grid-shaped metal foil 21, rigid micro-column array 22, row line 23, column line 24 and cross insulating pad 25.
Detailed Description
The invention will be described in further detail with reference to the following figures and examples, which are intended to facilitate the understanding of the invention without limiting it.
As shown in fig. 1, a 4 × 3 flexible tactile sensor array is stacked in two layers, and includes a flexible substrate 01 and a tactile sensor array 02 from bottom to top. The tactile sense array 02 includes 4 × 3 tactile sense units and an interconnection line network connecting each tactile sense unit.
As shown in fig. 2, the tactile sensing unit is a grid-shaped metal foil 21 encapsulated by a conformal polymer package, and a rigid micro-pillar array 22 is integrated on the grid-shaped metal foil 21.
For easy understanding of the interconnection network, as shown in fig. 3, 4 × 3 rectangular wave-shaped grid-shaped metal foils 21 are connected into an interconnection network formed by vertically crossing 4 row lines 23 and 3 column lines 24, and the row lines 23 and the column lines 24 are provided with crossing insulating pads 25 at crossing points.
In this embodiment, the grid-shaped metal foil 21 is a rectangular wave grid, and the flexible substrate 01 is made of a PDMS (polydimethylsiloxane) thin layer with a thickness of 200 μm; the material of the polymer substrate and the polymer encapsulation is PI (polyimide), and the thickness of the PI (polyimide) is 2.5 micrometers; the cross insulating pad 25 is made of PI with the thickness of 1 micron; the grid-shaped metal foil 21 and the interconnection line network adopt chromium-gold double-layer metal, and 100 nanometers of gold is bonded on the polymer substrate through 5 nanometers of chromium; the hard micro-column array 22 is made of light-cured resin, is in the shape of a cuboid and has the size of 20 × 35 microns.
Fig. 4 shows an enlarged schematic diagram of the tactile sensing unit. Under the contact pressure of the hard micro-column array 22, the grid-shaped metal foil 21 is pressed downwards after the pressure is amplified, and the grid-shaped metal foil 21 is stretched and bent along with the concave of the flexible substrate 01, so that the resistance of the grid-shaped metal foil 21 is changed. When the contact pressure is released, the substrate springs back rapidly due to the elasticity of the flexible substrate 01, and the shape and resistance of the barrier metal foil 21 are restored. Therefore, in the process of applying and releasing the contact pressure, the resistance of the touch sensing unit can make quick response through the extrusion of the hard micro-column and the concave deformation and quick rebound of the flexible substrate, so that the output electric signal is changed, and the function of sensing the pressure is realized.
One of the methods of making the flexible tactile sensor array of the present invention is described below.
(1) Preparation of Flexible substrates
The PDMS liquid prepolymer is adopted to prepare a flexible substrate with the thickness of 200 microns on a silicon wafer through spin coating and thermal curing, the spin coating can be used for obtaining flexible substrates with different thicknesses by controlling the rotating speed and time, and a mould can also be used for preparing flexible substrates with specific thicknesses.
(2) Preparation of tactile sensing array
Spin coating polymer PI (polyimide) on a clean glass sheet, and preparing a PI film with the thickness of 2.5 microns as a polymer substrate after curing. Photoetching and developing on a PI substrate, depositing 5 nm chromium, stripping the metal of 100 nm gold by using acetone, and preparing the rectangular wave type grid-shaped metal foil and the row line of the interconnection line network on the PI substrate. And spin-coating PI again, and curing to prepare the polymer package with the thickness of 1 micrometer.
And (3) spin-coating a photoresist on the structure, carrying out photoetching development, etching redundant PI by using an ICP (inductively coupled plasma etcher), preparing a PI cross insulation pad, and removing the photoresist by using acetone. Photoresist is spin-coated on the structure and is subjected to photoetching development, 5 nm of chromium is deposited, 100 nm of gold is stripped by utilizing acetone, and then the column line of the interconnection network is prepared. Spin coating PI again, curing, preparing a polymer package with the thickness of 2.5 microns, spin coating photoresist on the package, carrying out photoetching development, depositing 100 nm aluminum serving as a barrier layer, and etching redundant PI by using ICP. A photocurable resin was spin coated on this structure and developed photolithographically to produce an array of hard micropillars of 20 x 35 microns in size.
Finally, the substrate is placed in an alkaline developing solution to completely dissolve the aluminum. And soaking the substrate in hydrofluoric acid, wherein the hydrofluoric acid dissolves the surface of the substrate, so that the prepared touch sensing array is released from the substrate.
(3) Bonding of
Picking up the released tactile sensing array flat using a water-soluble adhesive tape, one side of the array being fully adhered to the tape and the other side being exposed, depositing a thin layer of chromium and a thin layer of silicon dioxide on the exposed side; and (3) after the flexible substrate is placed in a plasma cleaning machine and treated by oxygen, the water-soluble adhesive tape adhered with the touch sensor array and the flexible substrate are quickly bonded into a whole by hot pressing, and then the flexible substrate is placed in water to completely dissolve the water-soluble adhesive tape, so that the flexible touch sensor array is obtained.
The above-mentioned embodiment is to the technical solution and the beneficial effects of the present invention have been described in detail, it should be understood that the above is only the specific embodiment of the present invention, not used for limiting the present invention, any modification, supplement and equivalent replacement made within the principle scope of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A flexible tactile sensor array comprising a flexible substrate and a tactile sensor array, wherein the tactile sensor array comprises N x M tactile sensor units and a network of interconnecting lines connecting each tactile sensor unit;
the tactile sensing unit is a grid-shaped metal foil wrapped and encapsulated by conformal polymer, and a hard micro-column array is integrated on the grid-shaped metal foil;
the interconnection line network comprises N row lines and M column lines which are vertically crossed, crossed insulating pads are arranged at the crossed points of the row lines and the column lines, and the row lines and the column lines are wrapped and packaged by conformal polymer;
the touch sensing array is bonded on the flexible substrate.
2. The flexible tactile sensor array of claim 1 wherein the material of the flexible substrate is polydimethylsiloxane.
3. A flexible tactile sensor array according to claim 1, wherein the grid-like metal foil is a linear grid, a rectangular wave grid or a wave grid.
4. The flexible tactile sensor array of claim 1, wherein the grated metal foil is comprised of one or more layers of metal encapsulated by a conformal polymer wrap, each layer of metal having a thickness of 5 nanometers to 100 micrometers.
5. The flexible tactile sensor array of claim 1 wherein the polymeric material of the wrap-around package on the grated metal foil is polyimide, the polymeric wrap thickness being 2 microns to 200 microns.
6. The flexible tactile sensor array according to claim 1, wherein the hard micro-pillars in the hard micro-pillar array are rectangular solids, cylinders or cones, and the material is light-cured resin, light-cured polymer or photoresist.
7. A flexible tactile sensor array according to claim 1, wherein the cross insulating mat is polyimide 1-5 microns thick.
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