CN110987042A

CN110987042A - Manufacturing method of flexible stretchable sensor

Info

Publication number: CN110987042A
Application number: CN201911189465.5A
Authority: CN
Inventors: 董林玺; 管臻智
Original assignee: Hangzhou Dianzi University
Current assignee: Hangzhou Dianzi University
Priority date: 2019-11-28
Filing date: 2019-11-28
Publication date: 2020-04-10

Abstract

The invention discloses a manufacturing method of a flexible stretchable sensor. The invention firstly obtains the mould with the boss structure by photoetching and anisotropic etching on a silicon wafer. Secondly, dripping polydimethylsiloxane solution on a silicon wafer, degassing the polydimethylsiloxane solution, heating and curing, and stripping the flexible substrate with the boss structure. Then, a snake-shaped circuit is manufactured by laser direct writing of the copper sheet, and the snake-shaped circuit is transferred to the flexible substrate to serve as a lead connection sensitive area. Finally, the sensitive material of the sensor is transferred or sprayed onto the surface of the boss structure. According to the invention, the flexible substrate between the island-shaped boss structures and the snake-shaped metal lead provide integral stretching, and the stretching of the boss surface is reduced through the boss structures, so that the sensitive region of the sensor on the boss surface is basically not influenced by the stretching, the stretching performance of the sensor is improved, and the sensitive material of the sensor is protected from being reduced due to the stretching.

Description

Manufacturing method of flexible stretchable sensor

Technical Field

The invention relates to a novel sensor, in particular to a manufacturing method of a flexible stretchable sensor.

Background

Conventional electronic devices rely on rigid printed circuit board technology, which is advantageous for protecting electronic components from easy damage during use, but inevitably limits the ductility and flexibility of the electronic devices. Flexible electronics technology is an emerging electronic technology for fabricating organic/inorganic material electronic devices on flexible/ductile plastic or thin metal substrates for designing electronic products of various shapes, closer to the human body, and easy to use. The original functional structure of the electronic device is replaced by utilizing a flexible material or a flexible structure design, so that the core of the flexible electronic technology is formed.

Compared with a rigid electronic device, the flexible electronic device has the greatest difference and advantage that an electronic circuit of the flexible electronic device is not affected when the flexible electronic device bears large deformation, and the flexible electronic device has flexible performances of bendable shape, scalability and the like, and can still normally work under the stress condition. However, due to the unstable performance and the unpopular manufacturing method, electronic devices made of flexible materials are not mature, and the traditional silicon electronic devices cannot be stretched even though the process is mature. Therefore, it is necessary to use a special structure to enable the electronic device to be stretched.

Currently, two main structures are used to provide tensile properties to electronic devices. The first is to attach the electronic components to a pre-stretched elastomeric substrate. When the substrate strain is relieved, wrinkles appear in the elastic substrate, which increase the stretchability of the device. The second is to pattern discrete rigid islands in a softer substrate, with stretchable regions between individual rigid islands providing tensile properties throughout the device. However, both of the above methods have drawbacks, and the device manufactured by the first method can only be stretched in the pre-stretching direction, so that the stretching performance is limited; the second method has higher requirements on the rigid island in the whole device, only materials capable of bearing the tensile stress of the substrate can be used, and most sensitive materials of the sensor cannot bear larger tensile stress, so that the application range of the structure is limited.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides a novel manufacturing method of a flexible stretchable sensor. The structure used by the sensor can ensure that only the connecting part of the sensor is stretched when the sensor is stretched, and the stretching stress of the island-shaped boss structure where the sensitive area of the sensor is located is buffered by the inclined plane of the structure, so that the surface of the boss structure is basically not stretched, the stretching performance of the sensor is improved, and the sensitive area of the sensor is protected from being reduced due to stretching.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a method of making a flexible stretchable sensor comprising the steps of:

first, a silicon wafer is subjected to photolithography and anisotropic etching to obtain a mold having a mesa structure.

Secondly, dripping polydimethylsiloxane solution on a silicon wafer, degassing the polydimethylsiloxane solution, heating and curing, and stripping the flexible substrate with a boss structure, wherein the boss structure is provided with an inclined surface.

Then, a snake-shaped circuit is manufactured by laser direct writing of the copper sheet, and the snake-shaped circuit is transferred to the flexible substrate to be used as a lead of the sensor to be connected with the sensitive area of the upper surface of each boss structure.

And finally, transferring or spraying a sensitive material serving as a sensor to the upper surface of the boss structure to obtain the flexible stretchable sensor, wherein sensitive areas in the sensor are distributed in an array.

The invention has the beneficial effects that: the sensor provides integral stretching through the flexible substrate between the island-shaped boss structures and the serpentine metal wire, and the stretching of the boss surface is reduced through the boss structures, so that the sensitive area of the sensor on the boss surface is basically not influenced by the stretching, the stretching performance of the sensor is improved, and meanwhile, the sensitive material of the sensor is protected from being reduced in performance due to the stretching.

Drawings

FIG. 1 is a top view of the structure of the present invention;

FIG. 2 is a front view of the structure of the present invention;

FIG. 3 is an analysis of the stretching of the structure of the present invention;

in the figure 1: flexible substrate, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9: boss structure, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12: serpentine metal wire, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9: a sensor sensitive material.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The invention obtains the mould of the boss structure by photoetching and anisotropic etching of a silicon wafer, the shape of the boss structure can be controlled by photoetching, and the thickness of the boss structure can be controlled by etching. And secondly, dripping a polydimethylsiloxane solution containing a base prepolymer and a cross-linking agent onto a silicon wafer, degassing the polydimethylsiloxane solution, heating and curing, and stripping the flexible substrate with the boss structure. Then, a snake-shaped circuit is manufactured by laser direct writing of the copper sheet, and the snake-shaped circuit is transferred to the flexible substrate by using water-soluble glue to serve as a lead of the sensor to be connected with the sensitive area on each island. And finally, transferring or spraying materials such as graphene oxide and carbon nanotubes serving as sensitive materials of the sensor to the surface of the boss structure to obtain the sensor array.

When the sensor is stretched by an external force, a corresponding stress is generated inside the substrate. The boss structure has an inclined plane, the internal stress of the boss structure is continuously reduced along with the rise of the height of the boss, the strain of the structure is buffered along the inclined plane, and the stretching of the surface of the structure is far smaller than that of the whole sensor. The substrate between the island-shaped boss structures is stressed to generate large stretching, the snake-shaped circuit connected with the boss surface sensor generates stretching through deformation, and the substrate and the snake-shaped circuit provide integral stretching for the sensor.

The structure has wide application range, and can be used for arraying sensors made of materials with low tensile strength due to low tensile rate of the surface of the boss. Meanwhile, due to the manufacturing process of the sensor array structure, the boss structure and the snake-shaped circuit can be optimized according to different application occasions.

Example (b): in fig. 1, the mesa structures 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 on the flexible substrate 1 are uniformly distributed, and the sensor sensitive materials 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9 are respectively distributed on the surface of each mesa structure and are connected with each other through serpentine metal wires 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12.

In fig. 2, the component numbers are the same as those in fig. 1, and are the front view of the structure of the present invention, the heights of the serpentine metal wires 3.4, 3.5, 3.7 and 3.8 are very small, i.e. each metal wire is very thin and easy to deform to provide tension; and the boss structures 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 and 2.9 have inclined surfaces, so that the stretching can be buffered, and the sensitive materials 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8 and 4.9 on the surface are not influenced by the stretching.

In fig. 3, when the sensor is stretched by an external force, the serpentine metal wires 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12 are deformed accordingly to provide stretching according to the stretching direction, and at the same time, the flexible substrate portions between the boss structures 2.1 and 2.2, 2.8, between the boss structures 2.9 and 2.3, 2.7, between the boss structures 2.5 and 2.4, 2.6, and the flexible substrate portions between the boss structures 2.7 and 2.6, 2.8, between the boss structures 2.9 and 2.1, 2.5, and between the boss structures 2.3 and 2.2, 2.4 are also stretched accordingly.

The working process of the invention is as follows: with reference to fig. 1 and 3, assuming that the sensor is stretched by a force in the horizontal direction, due to the buffering effect of the boss structures 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, and 2.9, the stress on the sensitive materials 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, and 4.9 on the boss surface is buffered, and basically no stretching occurs. While the flexible substrate portions between the plateau formations 2.1 and 2.2, 2.8, between the plateau formations 2.9 and 2.3, 2.7 and between the plateau formations 2.5 and 2.4, 2.6 are stretched. Meanwhile, the serpentine metal wires 3.1, 3.3, 3.5, 3.7, 3.9 and 3.11 are stretched by being deformed under stress. Both provide the overall horizontal direction induced stretch for the sensor as a whole.

In conclusion, the sensor uses a special stretching structure, the sensitive area is arranged on the surface of the special boss structure, so that the stretching stress applied to the sensor during stretching is buffered, basically no stretching is generated, the stretching of the sensor is provided by the substrate among the boss structures and the snake-shaped interconnection metal wires, the stretching performance of the sensor is improved, and meanwhile, the sensitive area of the sensor is protected from being reduced due to the stretching.

Claims

1. A method for manufacturing a flexible stretchable sensor, which comprises a flexible substrate and sensitive areas arranged on the flexible substrate in an array shape, wherein the sensitive areas are arranged on a boss structure, and the sensitive areas are connected with each other through a snake-shaped circuit, and the method is characterized in that:

firstly, photoetching and anisotropic etching are carried out on a silicon wafer to obtain a mould with a boss structure;

secondly, dripping a polydimethylsiloxane solution on a silicon wafer, degassing the polydimethylsiloxane solution, heating and curing, and stripping out a flexible substrate with a boss structure, wherein the boss structure is provided with an inclined surface;

then, a snake-shaped circuit is manufactured by laser direct writing of the copper sheet, and the snake-shaped circuit is transferred to the flexible substrate to be used as a lead of a sensor to be connected with the sensitive area of the upper surface of each boss structure;

and finally, transferring or spraying a sensitive material serving as a sensor onto the upper surface of the boss structure to obtain the flexible stretchable sensor.

2. A method of making a flexible stretchable sensor according to claim 1, characterized by: the shape of the boss structure is controlled by photolithography, and the thickness of the boss structure is controlled by etching.

3. A method of making a flexible stretchable sensor according to claim 1, characterized by: the polydimethylsiloxane solution is provided with a base prepolymer and a cross-linking agent.

4. A method of making a flexible stretchable sensor according to claim 1, characterized by: the serpentine circuit uses a water-soluble glue in the transfer.

5. A method of making a flexible stretchable sensor according to claim 1, characterized by: the sensitive material comprises graphene oxide and carbon nanotubes.