TWI708929B - Pressure sensor with a grid structure - Google Patents

Abstract

A pressure sensor with a grid structure is provided to improve upon the high cost of the conventional pressure sensor resulting from the multi-layered structure which leads to a high manufacturing cost. The pressure sensor includes a protective layer, a sensing layer coupled with a surface of the protective layer and including a grid structure formed by a plurality of threads interlacing in both the longitudinal and transverse directions, a conductive layer including an electrode area electrically connected to two ports and abutting the grid structure of the sensing layer, and a flexible substrate covering one face of the conductive layer facing away from the sensing layer. Each of the plurality of threads has a width. Two adjacent threads are spaced from each other at a distance. The protective layer and the sensing layer are stacked with each other at a height.

Description

Pressure sensor with grid structure

The present invention relates to an electronic sensing device, especially a pressure sensor with a grid structure with a simple structure.

Flexible, thin, malleable and foldable pressure sensor, widely used in wearable devices and various flexible electronics (Flexible Electronics) products, the pressure sensor can generate corresponding electrical properties according to the external force Therefore, by analyzing the generation position and reading change of the electrical signal, the status of the external force can be known.

The above-mentioned conventional pressure sensors can sense through mechanisms such as capacitance, piezoresistive effect, and piezoelectric effect. The conventional pressure sensors are made of different materials such as flexible substrates, conductive materials, semiconductors, and carbon nanotubes. The components with functional characteristics are laminated into a multi-layer structure. However, in order to take into account the requirements of sensing sensitivity and thinness, the conventional pressure sensor requires material development and complicated manufacturing processes to combine the multi-layer structure with limited thickness and maintain the sensing The performance results in an increase in the manufacturing cost of the conventional pressure sensor.

In view of this, the conventional pressure sensor does still need to be improved.

In order to solve the above problems, the object of the present invention is to provide a pressure sensor with a grid structure, which has a simple structure to simplify the manufacturing process and reduce the manufacturing cost.

The second objective of the present invention is to provide a pressure sensor with a grid structure, which can improve the pressure sensing sensitivity and select the pressure sensing range to be applied to different sensing requirements.

Another object of the present invention is to provide a pressure sensor with a grid structure that concentrates the sensing material on the sensing surface, which can reduce the material cost.

The elements and components described in the full text of the present invention use the quantifiers "one" or "one" for convenience and to provide the general meaning of the scope of the present invention; the present invention should be interpreted as including one or at least one, and single The concept of also includes the plural, unless it clearly implies other meanings.

The approximate terms such as "combination", "combination" or "assembly" mentioned in the full text of the present invention mainly include the types that can be separated without destroying the components after being connected, or the components can not be separated after being connected, which are common knowledge in the field Those can be selected based on the materials of the components to be connected or assembly requirements.

The pressure sensor with a grid structure of the present invention includes: a protective layer; a sensing layer combined with the surface of the protective layer; the sensing layer is a grid structure formed by crisscrossing several lines, each The width of the line is a line width, and the distance between two adjacent lines is a line distance. The height of the protective layer and the sensing layer is a thickness; a conductive layer is connected to two electrical connection ports by an electrode area, the electrode The area is attached to the grid structure of the sensing layer; and a flexible substrate covering the other side surface of the conductive layer relative to the sensing layer.

Accordingly, the pressure sensor with a grid structure of the present invention can simplify the multi-layer structure and reduce the amount of sensing materials through the sensor layer of the grid structure, and has the effects of simplifying the manufacturing process and reducing the manufacturing cost. , The grid structure can increase the deformation of the force and the change of the resistance value. It can also adjust the sensitivity, force range and stability of the pressure sensor by changing the size of the grid structure. It can be applied to different The pressure sensing requirement of the system has the functions of improving the sensing performance and increasing the application range.

Wherein, the material of the protective layer is polydimethylsiloxane. In this way, the protective layer can withstand external forces such as pulling and bending, and prevent electrical changes on the sensing layer from being interfered by the outside, which has the effect of protecting the sensing layer and improving the accuracy of pressure sensing.

Wherein, the sensing layer is a multi-walled carbon nanotube chemically modified by acid. In this way, the manufacturing process of the sensing layer can be simplified, and the manufacturing cost can be reduced.

Among them, the electrode area is a finger-like structure. In this way, the interdigitated electrode system can sense any small changes in the grid structure, and has the effect of improving the pressure sensing sensitivity.

Wherein, the material of the flexible substrate is polyethylene terephthalate. In this way, the flexible substrate can be moisture-proof, corrosion-resistant, and bend-resistant, and has the effect of protecting the sensing layer and the conductive layer.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, the preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings:

Please refer to Figure 1, which is a preferred embodiment of the pressure sensor with a grid structure of the present invention, which includes a protective layer 1, a sensing layer 2, a conductive layer 3 and a flexible substrate 4. The sensing layer 2 is located on the surface of the protective layer 1, the conductive layer 3 is combined with the sensing layer 2, so that the sensing layer 2 is sandwiched between the protective layer 1 and the conductive layer 3, and the flexible substrate 4 covers The conductive layer 3 is opposite to the other side surface of the sensing layer 2.

Please refer to Figure 1, the protective layer 1 preferably has high toughness and insulation, so that the protective layer 1 can withstand external forces such as pulling and bending, the protective layer 1 can also prevent the sensing layer 2 The electrical changes of the protective layer 1 are interfered by the outside. In this embodiment, the material of the protective layer 1 is polydimethylsiloxane (PDMS), which has low material cost and fast manufacturing process, and can also make the protective layer 1 easy It is bonded to other materials at room temperature, has low chemical activity and good biocompatibility, and is suitable for use in wearable devices.

The sensing layer 2 is bonded to the surface of the protective layer 1, so that the sensing layer 2 can undergo various bending and folding deformations with the protective layer 1. The sensing layer 2 is preferably a high-conductivity thin film material. In an embodiment, the sensing layer 2 is a multi-walled carbon nanotubes (Multi-Walled Carbon Nanotubes, MWCNTs) chemically modified by acid, which can improve the electrical properties of the sensing layer 2, simplify its manufacturing process, and reduce its Material cost, the sensing layer 2 can also be a single-walled carbon nanotube (CNT), carbon black (carbon black), graphene (Graphene) or a composite material thereof, and the present invention is not limited thereto.

Please refer to Figure 2, the sensing layer 2 is a grid structure formed by a number of lines crisscrossing each other, the width of each line is a line width W, the distance between two adjacent lines is a line distance S, the The overlapping height of the protective layer 1 and the sensing layer 2 is a thickness D.

Please refer to Figures 1 and 3, the conductive layer 3 is connected to two electrical connection ports 32 by an electrode region 31 of the interdigitated structure, and the electrode region 31 is attached to the grid structure of the sensing layer 2 , The electrode area 31 can measure the change in the resistance of the sensing layer 2 and the two electrical connection ports 32 can output the measurement result.

The flexible substrate 4 preferably has tensile strength, abrasion resistance, and electrical insulation. In this embodiment, the material of the flexible substrate 4 is polyethylene terephthalate (PET). The substrate 4 can prevent the signal transmission on the conductive layer 3 from being interfered by the outside, and has the functions of moisture resistance, corrosion resistance and bending resistance.

According to the aforementioned structure, when an external force acts on the protective layer 1 and the sensing layer 2, the resistance of the sensing layer 2 changes, and a sensing voltage can be measured by the conductive layer 3. The sensing The voltage corresponds to the change in the resistance value of the sensing layer 2. Please refer to Figures 4 to 6, which is the relationship between the sensing voltage and the external force. Also, adjust the line width W, the line distance S and the The thickness D specification can be observed in different trends of the relationship between the sensing voltage and the external force.

Please refer to Figure 4, the line width W is fixed to 1 mm and the thickness D is fixed to 1 mm, and the line spacing S is respectively 1 mm, 1.5 mm, and 2 mm for the sensors, with 0.5~10 Newton’s external force is used for pressure sensing. It can be seen from the relationship diagram that the sensor with a line spacing S of 1 mm and 1.5 mm has a larger ratio of the measured sensing voltage change to the external force change, which has better sensitivity. However, the change of the sensing voltage is less obvious to the external force above 7 Newtons, resulting in poor stability of the sensor and a narrow applicable measurement range; the sensor with a line spacing S of 2 mm, the measured sensing voltage The ratio of change to external force change is small, but the change of sensing voltage is relatively stable, which is suitable for a wide range of external force sensing.

Please refer to Figure 5, the line width W is fixed to 1 mm and the line spacing S is fixed to 1.5 mm, and the thickness D is 1 mm and 2 mm, respectively, with an external force of 0.5~10 Newton For pressure sensing, it can be seen from the relationship graph that the sensor with a thickness D of 1 mm has a more stable sensing voltage change than a sensor with a thickness D of 2 mm, and has better stability .

Please refer to Figure 6, the line spacing S is fixed to 1.5 mm and the thickness D is fixed to 1 mm, and the line width W is 1 mm and 2 mm, respectively, with an external force of 0.5~10 Newton For pressure sensing, it can be seen from the relationship diagram that the sensor with a line width W of 1 mm has a more stable sensing voltage change than the sensor with a line width W of 2 mm, and has better stability.

In summary, the pressure sensor with a grid structure of the present invention can simplify the multi-layer structure and reduce the amount of sensing materials through the sensor layer of the grid structure, which has the effects of simplifying the manufacturing process and reducing the manufacturing cost. In addition, the grid structure can increase the deformation of the force and the change of the resistance value. It can also adjust the sensitivity, force range and stability of the pressure sensor by changing the size of the grid structure. For different pressure sensing needs, it has the functions of improving sensing performance and increasing application range.

Although the present invention has been disclosed using the above-mentioned preferred embodiments, it is not intended to limit the present invention. Anyone who is familiar with the art without departing from the spirit and scope of the present invention may make various changes and modifications relative to the above-mentioned embodiments. The technical scope of the invention is protected. Therefore, the scope of protection of the invention shall be subject to the scope of the attached patent application.

1: protective layer 2: Sensing layer 3: conductive layer 31: Electrode area 32: electrical connection port 4: Flexible substrate W: line width S: line spacing D: thickness

[Figure 1] An exploded perspective view of a preferred embodiment of the present invention. [Figure 2] A partially assembled perspective view of a preferred embodiment of the present invention. [Figure 3] A cross-sectional view of a preferred embodiment of the present invention. [Figure 4] The relationship between the sensing voltage and the external force of the sensors with different line distances. [Figure 5] The relationship between the sensing voltage and external force of sensors with different thicknesses. [Figure 6] The relationship between the sensing voltage and external force of sensors with different line widths.

1: protective layer

2: Sensing layer

3: conductive layer

31: Electrode area

32: electrical connection port

4: Flexible substrate

Claims (5)

A pressure sensor with a grid structure, including: A protective layer A sensing layer is combined with the surface of the protective layer. The sensing layer is formed by a grid structure of several lines crisscrossing each other. The width of each line is one line width, and the distance between two adjacent lines is one line pitch. The overlapping height of the protective layer and the sensing layer is a thickness; A conductive layer, two electrical connection ports are respectively connected by an electrode area, the electrode area is attached to the grid structure of the sensing layer; and A flexible substrate covering the other side surface of the conductive layer opposite to the sensing layer. The pressure sensor with a grid structure as described in item 1 of the scope of patent application, wherein the material of the protective layer is polydimethylsiloxane. The pressure sensor with a grid structure as described in item 1 of the scope of patent application, wherein the sensing layer is a multi-walled carbon nanotube that has been chemically modified by acid. The pressure sensor with a grid structure as described in item 1 of the scope of patent application, wherein the electrode area is a finger structure. The pressure sensor with a grid structure as described in item 1 of the scope of patent application, wherein the material of the flexible substrate is polyethylene terephthalate.

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