A large-area thin-film pressure sensor

Abstract

The present invention provides a large-area thin film pressure sensor. The large-area thin film pressure sensor comprises: an upper packaging layer and a lower packaging layer; an electrode layer, which is arranged on the lower packaging layer and connected to an external power source; a nano-sensitive layer, which is formed on the upper packaging layer in a thin film form; and a flexible support layer, which is arranged between the nano-sensitive layer and the electrode layer and is configured to allow the nano-sensitive layer and the electrode layer to contact when the large-area thin film pressure sensor is subjected to external pressure, and to completely separate the nano-sensitive layer and the electrode layer when the external pressure is removed. The large-area thin film pressure sensor of the present invention greatly improves the consistency and stability of the output performance of the thin film pressure sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure detection, and in particular to a large-area thin film pressure sensor. Background Art

[0002] Thin film pressure sensors have good flexibility and ductility, and can even be bent or folded freely. They have flexible and diverse structures and can be arranged arbitrarily according to the requirements of the measurement conditions. They can easily detect complex measurements. Therefore, new flexible sensors are widely used in electronic skin, medical care, electronics, electrical engineering, sports equipment, textiles, aerospace, environmental monitoring and other fields.

[0003] However, when the area of ​​the thin film pressure sensor is large, it faces the problem of self-collapse and slow deformation recovery. The traditional thin film pressure sensor includes an electrode layer and a sensitive film layer. When the thin film pressure sensor is subjected to pressure, the electrode layer and the sensitive film layer come into contact with each other, causing the resistance of the device to change, thereby detecting the external pressure. Figure 1 FIG. 1 shows a resistance-time variation curve of a large-area thin film pressure sensor in the prior art. Figure 1 As shown, when the large-area thin film pressure sensor is subjected to external pressure, the sensitive film layer contacts the electrode layer, and the resistance begins to change. As the pressure decreases, the resistance change slowly returns to zero. However, since the film is too large and the tension is insufficient, self-collapse will occur, and the film cannot return to its original state. Therefore, when the external force is completely removed, there is still a certain contact between the sensitive film layer and the electrode layer, and the resistance cannot return to its original state. There will be a difference of R1, and the recovery process is relatively slow, requiring 3s to recover. Summary of the invention

[0004] One purpose of the present invention is to solve the technical problem in the prior art that large-area thin film pressure sensors cannot return to their original state due to self-collapse after being subjected to external pressure, resulting in poor consistency and stability in the output performance of the thin film pressure sensors.

[0005] A further object of the present invention is to prevent the large-area thin-film pressure sensor from collapsing and to accelerate the recovery of the resistance of the large-area thin-film pressure sensor to its original state.

[0006] In particular, the present invention provides a large-area thin film pressure sensor, comprising:

[0007] An upper packaging layer and a lower packaging layer;

[0008] An electrode layer is formed on the lower packaging layer, and the electrode layer is connected to an external power source;

[0009] A nano-sensitive layer is formed on the upper packaging layer in a thin film form;

[0010] A flexible support layer is arranged between the nano-sensitive layer and the electrode layer, and is configured to allow the nano-sensitive layer and the electrode layer to contact when the large-area thin film pressure sensor is subjected to external pressure, and to completely separate the nano-sensitive layer and the electrode layer when the external pressure is removed.

[0011] Optionally, the nano-sensitive layer and the electrode layer are both configured to be continuous;

[0012] The electrode layer and the nano-sensitive layer are arranged in an aligned manner up and down.

[0013] Optionally, the area of ​​the nano-sensitive layer is greater than or equal to a first preset area, and the first preset area is the minimum area of ​​the nano-sensitive layer that can self-collapse when in a suspended state.

[0014] Optionally, the area of ​​the electrode layer is greater than or equal to a second preset area, and the second preset area is the minimum area of ​​the nano-sensitive layer that can self-collapse when in a suspended state.

[0015] Optionally, the flexible supporting layer is configured to provide a plurality of supporting points for the nanosensitive layer and / or the electrode layer gradually from the outer edge region of the nanosensitive layer and / or the electrode layer to the central region.

[0016] Optionally, the multiple supporting points of the flexible supporting layer are arranged in an array.

[0017] Optionally, the flexible supporting layer is configured in a grid shape, a zigzag shape, a concentric ring shape or a maze shape.

[0018] Optionally, the electrode layer is configured as an interdigitated electrode;

[0019] The electrode density of the interdigitated electrodes matches the density of the multiple supporting points of the flexible supporting layer, so as to prevent the flexible supporting layer from affecting the contact between the nano-sensitive layer and the electrode layer when the large-area thin film pressure sensor is subjected to external pressure, and to support the nano-sensitive layer and the electrode layer when the external pressure is removed, so that the nano-sensitive layer and the electrode layer can be completely separated.

[0020] Optionally, the electrode density of the interdigitated electrodes and the density of the multiple supporting points of the flexible supporting layer are set to allow the nano-sensitive layer to contact at least four electrodes of the interdigitated electrodes simultaneously when the large-area thin film pressure sensor is subjected to external pressure.

[0021] Optionally, a groove is formed on the lower packaging layer, and the groove matches the shape of the electrode layer to allow the electrode layer to be embedded in the groove and make the upper surface of the electrode layer flush with the upper surface of the lower packaging layer.

[0022] According to the solution of the present invention, a flexible supporting layer is added between the electrode layer and the nano-sensitive layer, and the flexible supporting layer is constructed to allow the nano-sensitive layer and the electrode layer to contact when the large-area thin film pressure sensor is subjected to external pressure, and the nano-sensitive layer and the electrode layer are completely separated when the external pressure is removed. This can solve the technical problem that the resistance of the large-area thin film pressure sensor cannot be restored to its original state due to the self-collapse problem, thereby greatly improving the consistency of the output performance of the thin film pressure sensor.

[0023] Furthermore, by designing the structure of the flexible support layer and considering the structure of the interdigital electrodes during the design process, the electrode density of the interdigital electrodes is matched with the density of multiple supporting points of the flexible support layer, so as to avoid the flexible support layer affecting the contact between the nano-sensitive layer and the electrode layer when the large-area thin film pressure sensor is subjected to external pressure, and to support the nano-sensitive layer and the electrode layer when the external pressure is removed, and to enable the nano-sensitive layer and the electrode layer to be completely separated. This can greatly speed up the time for the resistance of the large-area thin film pressure sensor to return to its original state, achieving the purpose of rapid recovery with a recovery time of about 1 second.

[0024] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0026] Figure 1 The figure shows a resistance-time variation curve of a large-area thin film pressure sensor in the prior art;

[0027] Figure 2 A schematic structural diagram of a large-area thin-film pressure sensor according to an embodiment of the present invention is shown;

[0028] Figure 3 shows a voltage-current diagram of a large-area thin-film pressure sensor under different pressures according to an embodiment of the present invention;

[0029] Figure 4It shows a sensitivity curve diagram of three tests of the same large-area thin film pressure sensor according to one embodiment of the present invention;

[0030] In the figure: 1-upper packaging layer, 2-nanosensitive layer, 3-flexible support layer, 4-lower packaging layer, 5-electrode layer. DETAILED DESCRIPTION

[0031] Figure 2 FIG. 2 shows a schematic structural diagram of a large-area thin-film pressure sensor according to an embodiment of the present invention. Figure 2 As shown, the large-area thin film pressure sensor comprises an upper packaging layer 1, a lower packaging 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 packaging layer 4, and the electrode layer 5 is connected to an external power source. The nano-sensitive layer 2 is formed on the upper packaging layer 1 in a thin 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 the nano-sensitive layer 2 and the electrode layer 5 to contact when the large-area thin film pressure sensor is subjected to external pressure, and to completely separate the nano-sensitive layer 2 and the electrode layer 5 when the external pressure is removed.

[0032] According to the solution of the present invention, by adding a flexible supporting layer 3 between the electrode layer 5 and the nano-sensitive layer 2, and making the flexible supporting layer 3 to allow the nano-sensitive layer 2 and the electrode layer 5 to contact when the large-area thin film pressure sensor is subjected to external pressure, the nano-sensitive layer 2 and the electrode layer 5 are completely separated when the external pressure is removed, thereby solving the technical problem that the resistance of the large-area thin film pressure sensor cannot be restored to its original state due to the self-collapse problem, thereby greatly improving the consistency of the output performance of the thin film pressure sensor.

[0033] In one embodiment, the electrode layer 5 and the nano-sensitive layer 2 are both continuous, that is, the electrode layer 5 is composed of one electrode, and the thin film structure of the nano-sensitive layer 2 is continuous. In addition, the electrode layer 5 and the nano-sensitive layer 2 are arranged vertically and aligned.

[0034] The shape of the upper encapsulation layer 1 and the lower encapsulation layer 4 can be any shape, for example, it can be circular, elliptical, square, rectangular, etc. The electrode layer 5 can be, for example, a forked electrode, which is composed of a plurality of comb-shaped or finger-shaped electrodes arranged periodically, and the forked electrode can be, for example, circular, rectangular or square. The material of the electrode layer 5 can be selected from metals such as copper, aluminum, silver, etc., and can be made by magnetron sputtering, micro-nano processing, vacuum coating technology and laser scribing technology. In one embodiment, the area of ​​the electrode layer 5 is greater than or equal to the second preset area, and the second preset area is the minimum area where the nano-sensitive layer 2 can self-collapse when in a suspended state. Here, "suspended state" means that the lower encapsulation layer 4 and the electrode layer 5 arranged thereon are taken as a whole, so that the electrode layer 5 is in an inverted state facing downward. If there is no flexible support layer 3 between the nano material layer and the electrode layer 5, then in the suspended state and when the electrode layer 5 has a large area, the electrode layer 5 is at risk of self-collapse, and when the device is subjected to external pressure, the collapsed electrode layer 5 is not easy to return to the initial state.

[0035] The area of ​​the nano-sensitive layer 2 is greater than or equal to the first preset area, and the first preset area is the minimum area of ​​the nano-sensitive layer 2 that can self-collapse when in a suspended state. Here, "suspended state" means that the upper encapsulation layer 1 and the nano-sensitive layer 2 arranged thereon are taken as a whole, so that the nano-sensitive layer 2 is in an inverted state facing downward. If there is no flexible support layer 3 between the nano-material layer and the electrode layer 5, then in the suspended state and when the area of ​​the nano-sensitive layer 2 is large, the nano-sensitive layer 2 is at risk of self-collapse, and when the device is subjected to external pressure, the collapsed nano-sensitive layer 2 is not easy to return to the initial state. The nano-sensitive layer 2 is preferably selected as a conductive nano-ink material, and the components of the conductive nano-ink material include conductive carbon materials, polymers, and inorganic semiconductor materials, etc. The conductive carbon material can be, for example, amorphous carbon, graphene, carbon nanotubes, etc. The polymer can be, for example, PDMS, and the role of the polymer is to serve as a filler and film-forming. The inorganic semiconductor material can be, for example, silicon dioxide, which can be used as a dispersant. The preparation method of the nano-sensitive layer 2 includes dip coating, spin coating, screen printing and inkjet printing.

[0036] The flexible support layer 3 is configured to provide multiple support points for the nano-sensitive layer 2 and / or the electrode layer 5 gradually from the outer edge area of ​​the nano-sensitive layer 2 and / or the electrode layer 5 to the central area. The multiple support points of the flexible support layer 3 are arranged in an array. The multiple support points can be expanded to be understood as support points, support lines or support surfaces. For example, the flexible support layer 3 can be configured in a grid shape, a zigzag shape, a concentric ring shape or a maze shape. The material of the flexible support layer 3 is an insulating material, for example, it can be liquid glue, solid glue, glue film and UV glue. In this embodiment, the packaging of the large-area thin film pressure sensor can be bonded and packaged by liquid glue, solid glue, glue film, UV glue or injection molding.

[0037] The structural design of the flexible support layer 3 is to consider the structure of the electrode layer 5. The electrode density of the interdigital electrodes is matched with the density of the multiple supporting points of the flexible support layer 3, so as to prevent the flexible support layer 3 from affecting the contact between the nano-sensitive layer 2 and the electrode layer 5 when the large-area thin film pressure sensor is subjected to external pressure, and to support the nano-sensitive layer 2 and the electrode layer 5 when the external pressure is removed, so that the nano-sensitive layer 2 and the electrode layer 5 can be completely separated. The following is an example of a large-area thin film pressure sensor device in the shape of a racket.

[0038] The upper packaging layer 1 and the lower packaging layer 4 of the large-area thin film pressure sensor both have a head and a neck connected to the head. The heads of the upper packaging layer 1 and the lower packaging layer 4 are both configured in an elliptical shape. The lower packaging layer 4 is also configured with a groove, the shape of which matches the shape of the electrode layer 5, and the groove extends from the head of the lower packaging layer 4 to the neck, so that the electrode layer 5 is embedded in the groove and extends from the head of the lower packaging layer 4 to the neck, and the upper surface of the electrode layer 5 is flush with the upper surface of the lower packaging layer 4. Since the electrode layer 5 is embedded in the groove of the lower packaging layer 4, the self-collapse problem of the electrode layer 5 can be further avoided.

[0039] The electrode layer 5 is configured to be elliptical, consistent with the shape of the lower packaging layer 4, and the electrode layer 5 is selected as a forked electrode. The forked electrode is periodically arranged in the form of an elliptical array by a plurality of finger-shaped or comb-shaped electrodes. The nano-sensitive layer 2 is a thin film, and can also be formed into an elliptical shape. The flexible support layer 3 can be, for example, a concentric ring, that is, composed of a plurality of concentric rings. The spacing between the plurality of finger-shaped or comb-shaped electrodes has a certain relationship with the spacing between the plurality of concentric rings, and not any spacing is acceptable. If the spacing is not appropriately selected, the device may fail to realize its basic function (the function of detecting pressure). The following is a detailed explanation through experimental verification data.

[0040] In the experiment, four different spacings were selected, namely 0.05mm, 0.5mm, 1.5mm and 3mm. When the spacing was 1.5mm, the final resistance change was the most obvious, and the resistance could be restored to the original state every time, and the resistance recovery time was about 1s, that is, when the spacing of multiple concentric rings was selected to be 1.5mm, the sensitivity of the device was the highest, and at the same time, the technical problem that the resistance of the device in the prior art could not be restored to the original state after being compressed and the resistance recovery process was slow could be solved. It was found through experimental verification that the spacing of the concentric rings is not limited to the above spacing, and can be any value in the range of 0.5-5mm. The spacing of the concentric rings reflects the density of the support points. The smaller the spacing, the greater the density, and the larger the spacing, the smaller the density. In other words, the support points of the flexible support layer 3 have an optimal density, and its optimal density can be determined according to the structure of the flexible support layer 3.

[0041] At the optimal density, the spacing between the electrodes in the electrode layer 5 will also affect the pressure detection performance. When the spacing between the electrodes is too sparse and greater than the optimal density, the nano-sensitive layer 2 cannot contact the electrode layer 5 after the device is compressed, and there will be no electrical signal. Although the spacing between the electrodes is too dense, it is helpful to improve the pressure detection performance, but it will increase the difficulty of the manufacturing process. Therefore, it is necessary to ensure that the nano-sensitive layer 2 can contact at least four electrodes after the device is compressed at the optimal density to achieve a balance between the manufacturing process and performance.

[0042] Figure 3 FIG. 1 shows a voltage-current diagram of a large-area thin-film pressure sensor under different pressures according to an embodiment of the present invention. Figure 3 It can be seen that under different pressures, the resistance will change significantly, and under the same pressure, the resistance can remain constant.

[0043] Figure 4 Figure 1 shows a sensitivity curve of three tests of the same large-area thin-film pressure sensor according to an embodiment of the present invention. Figure 4 It can be seen that after the large-area thin film pressure sensor is pressurized, the resistance undergoes an obvious relative change, indicating that the large-area thin film pressure sensor has a high sensitivity. At the same time, the results of the three measurements are not much different, indicating that the large-area thin film pressure sensor has better stability.

[0044] The large-area thin film pressure sensor has excellent elastic deformation ability, a wide range of material selection, low cost, simple manufacturing process, and stable performance of the large-area thin film pressure sensor, which can fundamentally solve the problem of poor cyclic stability of the sensing layer of the traditional thin film pressure sensor. Compared with traditional thin film pressure sensors, the large-area thin film pressure sensor of the present application has higher sensitivity, wider linear response range, and long-term cyclic stability and other performance, and has a wider range of applications. In addition, the large-area thin film pressure sensor adopts a strict packaging process, without gaps and grooves, and is more suitable for environments with high requirements such as dust-free and security.

[0045] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A large-area thin-film pressure sensor, characterized in that: include: An upper packaging layer and a lower packaging layer; An electrode layer, disposed on the lower packaging layer, and the electrode layer is connected to an external power source; A nano-sensitive layer is formed on the upper packaging layer in a thin film form; a flexible support layer, disposed between the nano-sensitive layer and the electrode layer, and configured to allow the nano-sensitive layer and the electrode layer to contact each other when the large-area thin film pressure sensor is subjected to external pressure, and to completely separate the nano-sensitive layer and the electrode layer when the external pressure is removed; The nano-sensitive layer and the electrode layer are both configured to be continuous; The electrode layer and the nano-sensitive layer are arranged vertically and aligned; The area of ​​the nano-sensitive layer is greater than or equal to a first preset area, and the first preset area is the minimum area in which the nano-sensitive layer can self-collapse when in a suspended state; The area of ​​the electrode layer is greater than or equal to a second preset area, and the second preset area is the minimum area of ​​the nano-sensitive layer that can self-collapse when in a suspended state.

2. The large-area thin-film pressure sensor according to claim 1, characterized in that: The flexible supporting layer is configured to provide a plurality of supporting points for the nano-sensitive layer and / or the electrode layer gradually from the outer edge region to the central region of the nano-sensitive layer and / or the electrode layer.

3. The large-area thin-film pressure sensor according to claim 2, characterized in that: The multiple supporting points of the flexible supporting layer are arranged in an array.

4. The large-area thin-film pressure sensor according to claim 3, characterized in that: The flexible supporting layer is configured in a grid shape, a zigzag shape, a concentric ring shape or a labyrinth shape.

5. The large-area thin-film pressure sensor according to claim 3 or 4, characterized in that: The electrode layer is configured as an interdigitated electrode; The electrode density of the interdigitated electrodes matches the density of the multiple supporting points of the flexible supporting layer, so as to prevent the flexible supporting layer from affecting the contact between the nano-sensitive layer and the electrode layer when the large-area thin film pressure sensor is subjected to external pressure, and to support the nano-sensitive layer and the electrode layer when the external pressure is removed, so that the nano-sensitive layer and the electrode layer can be completely separated.

6. The large-area thin-film pressure sensor according to claim 5, characterized in that: The electrode density of the interdigital electrodes and the density of the multiple supporting points of the flexible supporting layer are set so that when the large-area thin film pressure sensor is subjected to external pressure, the nano-sensitive layer is allowed to contact at least four electrodes of the interdigital electrodes simultaneously.

7. The large-area thin-film pressure sensor according to any one of claims 1, 3 and 4, characterized in that: A groove is formed on the lower packaging layer, and the groove matches the shape of the electrode layer to allow the electrode layer to be embedded in the groove and make the upper surface of the electrode layer flush with the upper surface of the lower packaging layer.

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