1. A large area thin film pressure sensor, comprising:

an upper encapsulation layer and a lower encapsulation layer;

the electrode layer is arranged on the lower packaging layer and is connected with an external power supply;

a nano-sensitive layer formed on the upper encapsulation layer in a film form;

a flexible support layer disposed between the nano-sensing layer and the electrode layer and configured to allow contact between the nano-sensing layer and the electrode layer when the large area thin film pressure sensor is subjected to an external pressure, such that the nano-sensing layer and the electrode layer are completely separated when the external pressure is removed.

2. The large area thin film pressure sensor of claim 1, wherein the nanosensor layer and the electrode layer are both configured to be continuous;

the electrode layer and the nanometer sensitive layer are arranged in an up-and-down alignment mode.

3. The large area thin film pressure sensor of claim 2, wherein the area of the nano-sensing layer is greater than or equal to a first predetermined area, the first predetermined area being a minimum area where the nano-sensing layer can self-collapse in a suspended state.

4. The large area thin film pressure sensor of claim 2, wherein the area of the electrode layer is greater than or equal to a second predetermined area, the second predetermined area being a minimum area where the nano-sensing layer can self-collapse in a suspended state.

5. The large area thin film pressure sensor of any of claims 1-4, wherein the flexible support layer is configured to provide a plurality of support points for the nano-sensitive layer and/or the electrode layer from an outer edge region to a central region of the nano-sensitive layer and/or the electrode layer.

6. The large area membrane pressure sensor as in claim 5, wherein the plurality of support points of the flexible support layer are arranged in an array.

7. The large area thin film pressure sensor of claim 6, wherein the flexible support layer is configured in a grid, zigzag, concentric circles, or labyrinth type.

8. The large area thin film pressure sensor according to claim 6 or 7, wherein the electrode layers are configured as interdigitated electrodes;

the electrode density of the interdigital electrode and the density of the plurality of supporting points of the flexible supporting layer are matched with each other, so that when the large-area thin film pressure sensor is subjected to external pressure, the flexible supporting layer is prevented from influencing the contact between the nanometer sensitive layer and the electrode layer, the nanometer sensitive layer and the electrode layer are supported when the external pressure is removed, and the nanometer sensitive layer and the electrode layer can be completely separated.

9. The large area thin film pressure sensor according to claim 8, wherein the electrode density of the interdigital electrodes and the density of the plurality of support points of the flexible support layer are set to allow the nano-sensitive layer to contact at least four electrodes of the interdigital electrodes simultaneously when the large area thin film pressure sensor is subjected to an external pressure.

10. The large area thin film pressure sensor of any of claims 1-4, 6 and 7, wherein a groove is formed on the lower encapsulation layer, the groove matching the shape of the electrode layer to allow the electrode layer to be embedded within the groove and having the upper surface of the electrode layer flush with the upper surface of the lower encapsulation layer.

Background

The film pressure sensor has good flexibility and ductility, can be freely bent or even folded, has flexible and various structural forms, can be randomly arranged according to the requirements of measurement conditions, and can conveniently detect complex measured values. Therefore, the novel flexible sensor is widely applied to the fields of electronic skin, medical care, electronics, electricians, sports equipment, textiles, aerospace, environmental monitoring and the like.

However, when the area of the membrane pressure sensor is large, there is a problem in that self-collapse and slow recovery of deformation are encountered. The traditional film pressure sensor comprises an electrode layer and a sensitive film layer, and when the film pressure sensor is stressed, the electrode layer and the sensitive film layer are close to each other and contact with each other, so that the resistance of a device changes, and the external pressure is detected. Fig. 1 shows a resistance-time curve of a large area thin film pressure sensor of the prior art. As shown in fig. 1, when the large-area thin film pressure sensor is under external pressure, the sensitive thin film layer contacts with the electrode layer, the resistance begins to change, and the resistance changes to zero slowly along with the reduction of the pressure, however, because the thin film is too large and the tension is not enough, the problem of self-collapse can be generated, and the thin film cannot return to the original state, so that after the external force is completely removed, a certain contact still exists between the sensitive thin film layer and the electrode layer, the resistance cannot return to the original state, and there is a difference of R1, and the return process is slow, and 3s return time is needed.

Disclosure of Invention

The invention aims to solve the technical problems that in the prior art, due to the self-collapse problem of a large-area film pressure sensor after being subjected to external pressure, a film cannot be restored to an original state, so that the output performance consistency and the stability of the film pressure sensor are poor.

It is a further object of the present invention to prevent collapse of the large area thin film pressure sensor and to speed up the recovery of the resistance of the large area thin film pressure sensor to the original state.

In particular, the present invention provides a large area thin film pressure sensor comprising:

an upper encapsulation layer and a lower encapsulation layer;

the electrode layer is formed on the lower packaging layer and is connected with an external power supply;

a nano-sensitive layer formed on the upper encapsulation layer in a film form;

a flexible support layer disposed between the nano-sensing layer and the electrode layer and configured to allow contact between the nano-sensing layer and the electrode layer when the large area thin film pressure sensor is subjected to an external pressure, such that the nano-sensing layer and the electrode layer are completely separated when the external pressure is removed.

Optionally, the nanosensor layer and the electrode layer are both configured to be continuous;

the electrode layer and the nanometer sensitive layer are arranged in an up-and-down alignment mode.

Optionally, the area of the nano-sensitive layer is greater than or equal to a first preset area, where the first preset area is a minimum area where the nano-sensitive layer can self-collapse when in a suspended state.

Optionally, the area of the electrode layer is greater than or equal to a second preset area, where the second preset area is a minimum area where the nano sensitive layer can self-collapse in a suspended state.

Optionally, the flexible support layer is configured to provide a plurality of support points for the nano-sensitive layer and/or the electrode layer from an outer edge region to a central region of the nano-sensitive layer and/or the electrode layer.

Optionally, the plurality of support points of the flexible support layer are arranged in an array.

Optionally, the flexible support layer is configured in a grid, zigzag, concentric circular, or labyrinth pattern.

Optionally, the electrode layer is configured as an interdigitated electrode;

the electrode density of the interdigital electrode and the density of the plurality of supporting points of the flexible supporting layer are matched with each other, so that when the large-area thin film pressure sensor is subjected to external pressure, the flexible supporting layer is prevented from influencing the contact between the nanometer sensitive layer and the electrode layer, the nanometer sensitive layer and the electrode layer are supported when the external pressure is removed, and the nanometer sensitive layer and the electrode layer can be completely separated.

Optionally, the electrode density of the interdigital electrode and the density of the plurality of support points of the flexible support layer are set to allow the nano-sensitive layer to contact at least four electrodes of the interdigital electrode simultaneously when the large-area thin film pressure sensor is subjected to external pressure.

Optionally, a groove is formed on the lower packaging layer, and the shape of the groove is matched with that of the electrode layer, so that the electrode layer is allowed to be embedded into the groove, and the upper surface of the electrode layer is flush with the upper surface of the lower packaging layer.

According to the scheme of the invention, the flexible supporting layer is additionally arranged between the electrode layer and the nano sensitive layer, and is constructed to allow the nano sensitive layer to be contacted with the electrode layer when the large-area film pressure sensor is subjected to external pressure, and the nano sensitive layer is completely separated from the electrode layer when the external pressure is removed, so that the technical problem that the resistance of the large-area film pressure sensor cannot be restored to the original state due to the self-collapse problem can be solved, and the consistency of the output performance of the film pressure sensor is greatly improved.

Furthermore, by designing the structure of the flexible supporting layer and considering the structure of the interdigital electrode in the design process, the electrode density of the interdigital electrode and the density of a plurality of supporting points of the flexible supporting layer are matched with each other, so that when the large-area thin film pressure sensor is subjected to external pressure, the flexible supporting layer is prevented from influencing the contact between the nano sensitive layer and the electrode layer, the nano sensitive layer and the electrode layer are supported when the external pressure is removed, and the nano sensitive layer and the electrode layer can be completely separated. Therefore, the time for the resistance of the large-area film pressure sensor to return to the original state can be greatly shortened, and the purpose of quick return of about 1s of return time is achieved.

The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments thereof, taken in conjunction with the accompanying drawings.

Drawings

Some specific embodiments of the invention will be described in detail hereinafter, by way of illustration and not limitation, with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:

FIG. 1 illustrates a resistance versus time graph of a prior art large area thin film pressure sensor;

FIG. 2 shows a schematic block diagram of a large area membrane pressure sensor in accordance with one embodiment of the present invention;

FIG. 3 illustrates a voltage-current diagram for a large area thin film pressure sensor at different pressures according to one embodiment of the present invention;

FIG. 4 shows sensitivity profiles of the same large area thin film pressure sensor tested three times separately in accordance with one embodiment of the present invention;

in the figure: 1-upper packaging layer, 2-nanometer sensitive layer, 3-flexible supporting layer, 4-lower packaging layer and 5-electrode layer.

Detailed Description

FIG. 2 shows a schematic block diagram of a large area membrane pressure sensor according to one embodiment of the invention. As shown in fig. 2, the large area thin film pressure sensor includes an upper encapsulation layer 1, a lower encapsulation layer 4, an electrode layer 5, a nano-sensitive layer 2, and a flexible support layer 3. The electrode layer 5 is formed on the lower encapsulation layer 4, and the electrode layer 5 is connected to an external power source. The nano-sensitive layer 2 is formed on the upper sealing layer 1 in a film form. The flexible support layer 3 is arranged between the nano-sensitive layer 2 and the electrode layer 5 and is configured to allow contact between the nano-sensitive layer 2 and the electrode layer 5 when the large area thin film pressure sensor is subjected to an external pressure, such that the nano-sensitive layer 2 and the electrode layer 5 are completely separated when the external pressure is removed.

According to the scheme of the invention, the flexible support layer 3 is additionally arranged between the electrode layer 5 and the nano sensitive layer 2, the flexible support layer 3 is constructed to allow the nano sensitive layer 2 to be in contact with the electrode layer 5 when the large-area film pressure sensor is subjected to external pressure, and the nano sensitive layer 2 is completely separated from the electrode layer 5 when the external pressure is removed, so that the technical problem that the resistance of the large-area film pressure sensor cannot be restored to the original state due to the self-collapse problem can be solved, and the consistency of the output performance of the film pressure sensor is greatly improved.

In one embodiment, the electrode layer 5 and the nanosensor layer 2 are both continuous, i.e. the electrode layer 5 is constituted by one electrode and the thin-film structure of the nanosensor layer 2 is continuous. And, the electrode layer 5 and the nano-sensitive layer 2 are arranged in alignment above and below.

The shape of the upper and lower sealing layers 1 and 4 may be any shape, for example, circular, oval, square, rectangular, or the like. The electrode layer 5 may be, for example, an interdigital electrode, which is formed by a plurality of comb-shaped or finger-shaped electrodes periodically arranged, and the interdigital electrode may be, for example, a circle, a rectangle, a square, or the like. The material of the electrode layer 5 can be selected from copper, aluminum, silver and other metals, and can be prepared by magnetron sputtering, micro-nano processing, vacuum coating technology, laser scribing process and other methods. In one embodiment, the area of the electrode layer 5 is greater than or equal to a second predetermined area, which is the minimum area where the nano-sensitive layer 2 can self-collapse in the suspended state. Here, the "floating state" means an inverted state in which the lower package layer 4 and the electrode layer 5 provided thereon are integrated such that the electrode layer 5 faces downward. If the flexible support layer 3 is not arranged between the nanometer material layer and the electrode layer 5, the electrode layer 5 has a risk of self-collapse under the suspension state and under the condition that the area of the electrode layer 5 is large, and the collapsed electrode layer 5 is not easy to return to the initial state when the device is subjected to external pressure.

The area of the nano sensitive layer 2 is larger than or equal to a first preset area, and the first preset area is the minimum area of the nano sensitive layer 2 which can be subjected to self-collapse in a suspension state. Here, the "suspended state" refers to an inverted state in which the upper encapsulation layer 1 and the nano-sensitive layer 2 disposed thereon are integrated such that the nano-sensitive layer 2 faces downward. If the flexible supporting layer 3 is not arranged between the nanometer material layer and the electrode layer 5, the nanometer sensitive layer 2 has a risk of self-collapse under the suspension state and the large area of the nanometer sensitive layer 2, and the collapsed nanometer sensitive layer 2 is not easy to return to the initial state when the device is subjected to external pressure. The nano-sensitive layer 2 is preferably selected from a conductive nano-ink material, the conductive nano-ink material comprises a conductive carbon material, a high molecular polymer, an inorganic semiconductor material and the like, and the conductive carbon material can be amorphous carbon, graphene, carbon nanotubes and the like. The high molecular polymer may be, for example, PDMS, and functions as a filler and a film. The inorganic semiconductor material may be selected, for example, as silica, which may act as a dispersant. The preparation method of the nano sensitive layer 2 comprises dip coating, spin coating, screen printing, ink jet printing and the like.

The flexible support layer 3 is configured to provide a plurality of support points for the nano-sensitive layer 2 and/or the electrode layer 5 from the outer edge area of the nano-sensitive layer 2 and/or the electrode layer 5 gradually towards the central area. The plurality of support points of the flexible support layer 3 are arranged in a matrix. The plurality of support points can be understood as an enlarged support point, support line or support surface. For example, the flexible support layer 3 may be configured in a lattice shape, a zigzag shape, a concentric circular ring shape, or a labyrinth shape. The material of the flexible supporting layer 3 is an insulating material, and may be, for example, liquid glue, solid glue, glue film, UV glue, and the like. In this embodiment, the package of the large area thin film pressure sensor may be a bonded package by liquid glue, solid glue, glue film, UV glue, or injection molding.

The structural design of the flexible support layer 3 is such that the structure of the electrode layer 5 is taken into account. The electrode density of the interdigital electrode is matched with the density of a plurality of supporting points of the flexible supporting layer 3, so that when the large-area film pressure sensor is subjected to external pressure, the flexible supporting layer 3 is prevented from influencing the contact of the nanometer sensitive layer 2 and the electrode layer 5, the nanometer sensitive layer 2 and the electrode layer 5 are supported when the external pressure is removed, and the nanometer sensitive layer 2 and the electrode layer 5 can be completely separated. The following description will be given taking a large-area thin-film pressure sensor device as an example in a racket shape.

The upper and lower package layers 1 and 4 of the large area thin film pressure sensor each have a head and a neck connected to the head. The heads of the upper and lower potting layers 1, 4 are each configured in an oval shape. The lower packaging layer 4 is also provided with a groove, the shape of the groove is matched with that of the electrode layer 5, the groove extends from the head part to the neck part of the lower packaging layer 4, so that the electrode layer 5 is embedded into the groove and extends from the head part to the neck part of the lower packaging layer 4, and the upper surface of the electrode layer 5 is flush with the upper surface of the lower packaging layer 4. The problem of self-collapse of the electrode layer 5 can be further avoided due to the embedding of the electrode layer 5 into the recess of the lower encapsulation layer 4.

The electrode layer 5 is configured in an oval shape, conforming to the shape of the lower encapsulation layer 4, and the electrode layer 5 is selected as an interdigitated electrode. The interdigital electrode is periodically arranged in an elliptical array by a plurality of interdigital or comb electrodes. The nano-sensitive layer 2 is a thin film and may be formed in an elliptical shape. The flexible support layer 3 may, for example, be of concentric circular shape, i.e. consist of a plurality of concentric circular rings. The spacing between the plurality of finger-like or comb-like electrodes and the spacing between the plurality of concentric rings have a relationship, not any spacing, and improper selection of the spacing may result in the device failing to perform its basic function (function of detecting pressure). The following is a detailed description of experimental validation data.

In the experiment, four different distances are selected, namely 0.05mm, 0.5mm, 1.5mm and 3mm respectively, when the distance is 1.5mm, the finally obtained resistance change is most obvious, the resistance can be recovered to the original state every time, and the resistance recovery time is about 1s, namely, when the distance of a plurality of concentric rings is selected to be 1.5mm, the sensitivity of the device is the highest, and the technical problems that the resistance can not be recovered to the original state after the device in the prior art is pressed and the resistance recovery process is slow can be solved. Experiments prove that the distance between the concentric rings is not limited to the above distance, and can be any value in the range of 0.5-5 mm. The spacing of the concentric rings reflects the density of the support points, with smaller spacing, higher density, and larger spacing, lower density. That is, the support points of the flexible support layer 3 have an optimal density, which can be determined according to the structure of the flexible support layer 3.

At an optimum density, the spacing of the individual electrodes in the electrode layer 5 also has an effect on the pressure sensing performance. When the distance between the electrodes is too sparse and is larger than the optimal density, the electrode layer 5 cannot be contacted by the nano sensitive layer 2 after the device is pressed, and no electric signal exists at the moment. The distance between each electrode is too close, which is helpful for improving the pressure detection performance, but the manufacturing process difficulty is increased, so that the manufacturing process and performance can be balanced by ensuring that the nano sensitive layer 2 can contact at least four electrodes after the device is pressed under the optimal density.

FIG. 3 shows a voltage-current diagram for a large area thin film pressure sensor at different pressures according to one embodiment of the present invention. As can be seen from fig. 3, the resistance changes significantly under different pressures, and the resistance can be maintained constant under the same pressure.

FIG. 4 shows sensitivity profiles of the same large area membrane pressure sensor tested three times each, according to one embodiment of the present invention. As can be seen from fig. 4, after the large-area thin-film pressure sensor is pressed, the resistance changes significantly, which indicates that the large-area thin-film pressure sensor has higher sensitivity, and the results of three measurements are not very different, which indicates that the large-area thin-film pressure sensor has better stability.

The large-area film pressure sensor has the advantages of good elastic deformation capacity, wide material selection, low cost, simple manufacturing process and stable performance, and can fundamentally solve the problem of poor circulation stability of the sensing layer of the traditional film pressure sensor. Compared with the traditional film pressure sensor, the large-area film pressure sensor has the advantages of higher sensitivity, wider linear response range, long-term cycle stability and the like, and is wider in application range. In addition, the large-area film pressure sensor adopts a strict packaging process, has no gap or slot, and is more suitable for environments with higher requirements on dust-free performance, security and the like.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.