CN110987246B - Flexible sensors and preparation and use methods of flexible sensors - Google Patents

Abstract

The application relates to a flexible sensor and a preparation and use method of the flexible sensor, wherein the flexible sensor comprises a containing cavity and at least two electric signal measuring devices; wherein: the accommodating cavity is filled with a liquid conductive medium; at least two electric signal measuring devices are respectively communicated with the accommodating cavity, and an included angle is formed between any two electric signal measuring devices and the connecting line between the accommodating cavity. By utilizing the fluidity of the liquid conductive medium in the accommodating cavity, when the liquid conductive medium is extruded under the action of external force in a certain direction, different amounts of liquid conductive medium can flow into the electric signal measuring device in different directions, and then the stress direction and the stress of the flexible sensor can be determined according to the inflow of the liquid conductive medium.

Description

Flexible sensors and preparation and use methods of flexible sensors

Technical field

The present invention relates to the technical field of flexible devices, and in particular to a flexible sensor and a method of preparing and using the flexible sensor.

Background technique

As the core technology of future personalized wearable medical equipment, flexible electronics has received widespread attention and support from all aspects. Flexible electronic devices (including circuits, sensors, electrodes, chips, etc.) have the advantages of good skin affinity, stretchability, and bendability as devices. The current demand for flexible electronic devices is no longer satisfied with functions such as bendability and stretchability. Sensor devices with directional or directivity are also an important part of the research on flexible electronic sensors.

The flexible sensor based on liquid metal deforms due to tension, which causes the resistance change of the liquid metal. Therefore, the resistance change value of the liquid metal can be detected and converted into a change in tension. However, current flexible sensors are mostly based on changes in the material itself and cannot have directionality or directivity, which greatly limits the application range of liquid metal flexible sensors.

Contents of the invention

This application provides a flexible sensor and a method for preparing and using the flexible sensor, which enables the flexible sensor to sense the magnitude and direction of external force, thereby expanding the application range of the flexible sensor.

A flexible sensor includes a receiving cavity and at least two electrical signal measuring devices; wherein:

The accommodation cavity is filled with liquid conductive medium;

At least two of the electrical signal measuring devices are respectively communicated with the accommodating cavity, and the connection between any two of the electrical signal measuring devices and the accommodating cavity has an included angle, for use in the accommodating cavity. After the liquid conductive medium is under pressure and filled into each of the electrical signal measuring devices respectively, the parameters of each of the electrical signal measuring devices are detected, and the force direction and force magnitude of the flexible sensor are determined based on the parameters.

In one embodiment, the electrical signal measurement device includes a valve structure and a capacitive sensor; the capacitive sensor includes a first electrode cavity and a second electrode cavity; the first electrode cavity and the second electrode cavity are spaced apart;

The first electrode cavity and the second electrode cavity are respectively connected to the accommodation cavity through the valve structure, and are used to induce corresponding capacitance according to the capacity of the liquid conductive medium entering the first electrode cavity and the second electrode cavity;

The valve structure is used to adjust the valve opening according to the magnitude and direction of the pressure;

When the flexible sensor is under pressure, the liquid conductive medium in the accommodation cavity is filled into the first electrode cavity and the second electrode cavity through the valve structure.

In one embodiment, the electrical signal measurement device further includes a solid electrode, the solid electrode includes a first electrode and a second electrode; the first electrode is connected to the first electrode cavity, and the second electrode is connected to the first electrode cavity. The second electrode cavity is connected and used to detect the capacitance value of the capacitive sensor.

In one embodiment, the valve structure includes a first conduit and a second conduit that are sleeved;

The first end of the first conduit is connected to the accommodation chamber, the first end of the second conduit is connected to the capacitive sensor, and the second end of the second conduit extends from the second end of the first conduit. into the first conduit and connect with it.

In one embodiment, the capacitive sensor includes an interdigital capacitance.

In one embodiment, a plurality of support structures are provided in the accommodation cavity, and the support structures extend toward the electrical signal measurement device along the center of the accommodation cavity.

In one embodiment, the included angles between any two adjacent electrical signal measuring devices and the containing cavity are equal.

A method for preparing a flexible sensor, the method comprising:

S1: Provide a flexible substrate mold, fill the flexible substrate mold with a flexible substrate precursor and solidify it to form a flexible substrate;

S2: Prepare an accommodation cavity and at least two electrical signal measurement devices on the flexible substrate, and fill the accommodation cavity with a liquid conductive medium; the electrical signal measurement device includes a valve structure and a capacitance sensor, and the capacitance sensor It is connected to the accommodation cavity through the valve structure, and the connection between any two electrical signal measuring devices and the accommodation cavity has an included angle;

S3: Encapsulate the liquid conductive medium to complete the preparation of the flexible sensor.

In one embodiment, step S1 includes:

providing a rigid substrate;

According to the corresponding shapes of the accommodation cavity and the electrical signal measurement device, print a first mold on the surface of the rigid substrate and solidify it to obtain the flexible substrate mold;

The flexible substrate precursor is filled into the flexible substrate mold until it is filled and solidified to form the flexible substrate.

In one embodiment, step S2 includes:

Print the accommodation cavity on the flexible substrate, and print the electrical signal measurement device in at least two directions of the accommodation cavity;

A liquid conductive medium is filled into the accommodation cavity, so that the surface of the liquid conductive medium is oxidized to form a fixed shape.

In one embodiment, step S2 includes:

According to the corresponding shapes of the accommodation cavity and the electrical signal measurement device, print a second mold on the flexible substrate and/or the flexible substrate mold and solidify it;

Filling the second mold with the precursor liquid material until it is filled and solidified;

Remove the second mold located in the containing cavity and the electrical signal measuring device;

A liquid conductive medium is filled into the accommodation cavity, so that the surface of the liquid conductive medium is oxidized to form a fixed shape.

In one embodiment, the electrical signal measurement device further includes a solid electrode, and the solid electrode is connected to the capacitive sensor.

In one embodiment, step S3 includes:

According to the corresponding shapes of the accommodation cavity and the electrical signal measurement device, print an upper mold on the flexible substrate mold and/or the flexible substrate and solidify it;

Fill the upper mold with the flexible substrate precursor until it is filled and solidified, so that the flexible substrate precursor coats the liquid conductive medium;

The flexible substrate mold and the upper mold are removed to obtain the flexible sensor.

A method of using the above-mentioned flexible sensor, the method includes:

Place the accommodation cavity of the flexible sensor on the surface of the body to be measured, and paste a plurality of the electrical signal measuring devices on the surface of the body to be measured in different directions;

Obtain parameters of each electrical signal measurement device;

The force direction and force magnitude on the surface of the object to be measured are determined based on the parameters.

The present application provides a flexible sensor and a method of preparing and using the flexible sensor. The flexible sensor includes an accommodation cavity and at least two electrical signal measuring devices; wherein: the accommodation cavity is filled with a liquid conductive medium; and the electrical signal measuring devices are respectively connected with The accommodating cavities are connected, and the connection between any two electrical signal measuring devices and the accommodating cavities has an included angle, so that the liquid conductive medium in the accommodating cavities is pressurized and filled into each respective After the electrical signal measuring device is installed, the parameters of each electrical signal measuring device are detected, and the force direction and force magnitude of the flexible sensor are determined based on the parameters. The flexible sensor provided by this application uses the fluidity of the liquid conductive medium in the accommodation cavity by arranging electrical signal measuring devices in multiple directions of the accommodation cavity. When there is external force to squeeze, the electrical signal measuring devices in different directions will flow into different amount of liquid conductive medium, and then the force direction and force magnitude of the flexible sensor can be determined based on the inflow amount of liquid conductive medium.

Description of the drawings

In order to explain the embodiments of the present application or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of a flexible sensor provided by an embodiment;

Figure 2 is a schematic structural diagram of a flexible sensor provided by another embodiment;

Figure 3 is a schematic structural diagram of a flexible sensor provided by another embodiment when subjected to external force;

Figure 4 is a schematic structural diagram of a valve structure provided in another embodiment;

Figure 5 is a schematic structural diagram of the valve structure in Figure 4 when it is longitudinally stretched according to an embodiment;

Figure 6 is a schematic structural diagram of the valve structure in Figure 4 when it is transversely stretched according to another embodiment;

Figure 7 is a flow chart of a flexible sensor preparation method provided in one embodiment;

Figure 8 is a flow chart of a method for using a flexible sensor provided in one embodiment.

Detailed ways

In order to facilitate understanding of the present application and to make the above-mentioned objects, features and advantages of the present application more obvious and understandable, the specific implementation modes of the present application are described in detail below in conjunction with the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present application, and the preferred embodiments of the present application are shown in the accompanying drawings. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and comprehensive understanding of the disclosure of the present application. The present application can be implemented in many other ways different from those described here. Those skilled in the art can make similar improvements without violating the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

In addition, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of this application, "plurality" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise expressly and specifically limited.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Figure 1 is a schematic structural diagram of a flexible sensor provided by an embodiment of the present application. As shown in Figure 1, a flexible sensor includes an accommodation cavity 110 and at least two electrical signal measurement devices 120; wherein:

The containing cavity 110 is filled with liquid conductive medium. At least two electrical signal measuring devices 120 are respectively connected with the accommodating cavity 110, and the connection between any two electrical signal measuring devices 120 and the accommodating cavity 110 has an included angle, so that the liquid conductive medium in the accommodating cavity 110 is under pressure. After filling each of the electrical signal measuring devices 120 respectively, the parameters of each electrical signal measuring device 120 are detected, and the force direction and force magnitude of the flexible sensor are determined according to the parameters.

The accommodation cavity 110 in this application is used to fill a liquid conductive medium, and a hard mold of the accommodation cavity 110 can be prepared by 3D printing rigid materials. Specifically, a filling space can be prepared for the flexible substrate precursor liquid material through a mold, the flexible substrate precursor liquid material can be filled into the filling space and heated and solidified to form a flexible substrate, and then a liquid conductive material can be prepared on the flexible substrate. The structure of the medium storage area is to fill the liquid conductive medium into the liquid conductive medium storage area, and finally fill the flexible substrate precursor liquid material again on the surface of the liquid conductive medium to complete the packaging of the structure of the liquid conductive medium storage area and form a holding cavity 110. It can be understood that the accommodation cavity 110 can also be obtained in other ways, which is not limited in this embodiment.

The shape of the accommodation cavity 110 may be circular, polygonal, elliptical, etc., and the specific shape is selected according to the actual situation. In the embodiment of the present application, the accommodation cavity 110 is circular. The circular accommodation cavity 110 can form flow channels in more directions. The flow of the liquid conductive medium will not be affected by the shape of the accommodation cavity 110, so that the flexibility can be determined more accurately. The force direction and magnitude of the sensor.

The liquid conductive medium can be liquid metal, salt water, sulfuric acid solution, etc., as long as there are a large number of anions and cations in the liquid. This application takes the liquid conductive medium as liquid metal as an example, because liquid metal with a certain degree of oxidation is easy to form. Liquid metal refers to an amorphous metal. Liquid metal can be regarded as a mixture composed of positive ionic fluid and free electron gas. Liquid metal is also a flowable liquid metal. This application fills liquid metal into the accommodation cavity 110 and utilizes the fluidity of the liquid metal. When the accommodation cavity 110 is acted upon by an external force, the liquid metal in the accommodation cavity 110 will be squeezed by the external force to flow. In this application, the liquid metal filled in the accommodation cavity 110 mainly includes liquid metals such as gallium indium tin alloy (Galinstan), gallium indium alloy (EGaIn), gallium zinc alloy (GaZn) or gallium tin alloy (GaSn). The specific composition of the filled liquid metal is not limited in this embodiment.

The flexible sensor provided by this application includes at least two electrical signal measuring devices 120. The at least two electrical signal measuring devices 120 are respectively connected with the accommodation cavity 110, and the connection between any two electrical signal measuring devices 120 and the accommodation cavity 110 has angle. In one embodiment, the included angles between two adjacent electrical signal measuring devices 120 and the containing cavity 110 are equal.

It can be seen from Figure 1 that the flexible sensor includes four electrical signal measuring devices 120. The four electrical signal measuring devices 120 are arranged in different directions of the accommodation cavity 110, and between any two adjacent electrical signal measuring devices 120 and the accommodation cavity 110 The angles between the lines are equal, so that the liquid metal in the accommodation cavity 110 has flow channels in multiple directions. When the accommodation cavity 110 is acted upon by an external force, the liquid metal will flow channels in different directions according to the direction and magnitude of the force. into different electrical signal measuring devices 120 . The electrical signal measuring device 120 senses corresponding parameters according to the flow rate of the liquid metal. By analyzing the parameters of multiple electrical signal measuring devices 120, the force direction and force magnitude of the flexible sensor can be determined. The flexible sensor provided by this application not only conforms to the kinematic design of the human body, but also achieves directionality measurement through parameters measured by multiple electrical signal measuring devices 120 . The parameters may include electrical performance parameters such as capacitance and voltage.

It can be understood that the number and placement positions of the electrical signal measuring devices 120 in FIG. 1 are only for illustration, and the specific number and placement positions are not limited. The number and location of the electrical signal measuring devices 120 can be freely adjusted according to actual conditions. Due to the need for directional function, the number of the electrical signal measuring devices 120 should be at least no less than two.

The flexible sensor provided by the embodiment of the present application includes an accommodation cavity 110 and at least two electrical signal measuring devices 120; wherein: the accommodation cavity 110 is filled with liquid metal; the at least two electrical signal measuring devices 120 are respectively connected with the accommodation cavity 110, and any The connection between the two electrical signal measuring devices 120 and the containing chamber 110 has an included angle, which is used to detect at least two electrical signal measuring devices 120 after the liquid metal in the pressurized containing chamber 110 is filled into the electrical signal measuring device 120 parameters, and determine the force direction and force magnitude of the flexible sensor based on the parameters. The flexible sensor provided by this application disposes electrical signal measuring devices 120 in multiple directions of the accommodation cavity 110 and utilizes the fluidity of the liquid metal in the accommodation cavity 110. When an external force is applied to squeeze the electrical signal measuring devices 120 in different directions, Different amounts of liquid metal will flow in, and the force direction and force magnitude of the flexible sensor can be determined based on the inflow amount of liquid metal.

In another embodiment, as shown in Figure 2, the electrical signal measuring device 120 includes a valve structure 121 and a capacitive sensor 122; the capacitive sensor 122 includes a first electrode cavity 1221 and a second electrode cavity 1222; the first electrode cavity 1221 and the second electrode cavity 1222. The two electrode cavities 1222 are spaced apart;

The first electrode cavity 1221 and the second electrode cavity 1222 are respectively connected with the accommodation cavity 110 through the valve structure 121, and are used to induce corresponding capacitance according to the capacity of the liquid conductive medium entering the first electrode cavity 1221 and the second electrode cavity 1222;

The valve structure 121 is used to adjust the valve opening according to the magnitude and direction of the pressure;

When the flexible sensor is under pressure, the liquid conductive medium in the accommodation cavity 110 is filled into the first electrode cavity 1221 and the second electrode cavity 1222 through the valve structure 121 .

Referring to FIGS. 2 and 3 , the valve structure 121 is disposed close to the accommodating chamber 110 , and the liquid metal in the accommodating chamber 110 flows into the capacitive sensor 122 through the valve structure 121 . During use of the flexible sensor, when the human body makes a directional stretching action and directional stretching of the accommodation cavity 110 of the flexible sensor (such as the combined action of stretching and bending of the elbow part), due to the liquid metal It has fluidity, so that the liquid metal in the accommodation cavity 110 will be squeezed into the capacitive sensor 122 . In addition, since the valve structure 121 is stretchable, the valve structure 121 in each direction deforms differently under the action of external force in a certain direction, so its ability to hinder liquid metal is different, so the electricity flowing into each direction is different. The amount of liquid metal in the signal measuring device 120 is also different. The direction and magnitude of the force can be determined by the magnitude of the electrical signal. Specifically, the valve structure 121 in the stretching direction is stretched longitudinally, and the flow channel of the valve structure 121 is elongated and thinned, which is not conducive to the extrusion of liquid metal, while the valve structure 121 perpendicular to the stretching direction is stretched transversely. Stretching, the flow channel of the valve structure 121 increases, which is conducive to the intrusion of liquid metal. Therefore, under the action of directional stretching, different amounts of liquid metal pour into the capacitive sensors 122 in different directions, so the capacitive sensors 122 in different directions sense The capacitor size is also different.

In another embodiment, a plurality of support structures 111 are provided in the accommodation cavity 110 , and the support structures 111 extend toward the electrical signal measurement device 120 from the center of the accommodation cavity 110 .

The number of support structures 111 can be equal to the number of electrical signal measurement devices 120, and the material on the side of the support structure 111 can be the same as the substrate material, for example, it can be PDMS. In this embodiment, by arranging the support structure 111 in the accommodation cavity 110, the inlet position of the valve structure 121 of the accommodation cavity 110 can be prevented from being blocked during the extrusion process.

In another embodiment, as shown in FIG. 4 , the valve structure 121 includes a flexible and sleeved first conduit 1211 and a second conduit 1212 ; the first end of the first conduit 1211 is connected to the accommodation chamber 110 , and the second conduit 1212 The first end of the second conduit 1212 is connected to the capacitive sensor 122, and the second end of the second conduit 1212 extends into the first conduit 1211 from the second end of the first conduit 1211 and is connected with it. The tubes of the first conduit 1211 and the second conduit 1212 The diameter gradually decreases in the direction extending from the first end to the second end.

When the valve structure 121 is longitudinally stretched, as shown in FIG. 5 , the flow channels of the first conduit 1211 and the second conduit 1212 are both in a contracted state, and the second end of the first conduit 1211 and the second end of the second conduit 1212 They are squeezed together, thereby shrinking the opening of the valve structure 121. The greater the force, the smaller the opening of the valve structure 121 until it is closed. It is difficult for the liquid metal in the accommodation chamber 110 to flow into the capacitive sensor 122 through the valve structure 121. When the accommodation chamber 110 is restored, the liquid metal flowing into the capacitive sensor 122 flows into the first conduit 1211 connected with the accommodation chamber 110 through the second conduit 1212, and then flows into the accommodation chamber 110.

When the valve structure 121 is stretched laterally, as shown in FIG. 6 , the flow channels of the first conduit 1211 and the second conduit 1212 are both in an expanded state, and the second end of the second conduit 1212 is no longer affected by the third conduit 1211 . The two ends are squeezed, so that the valve structure 121 is in an open state, and the liquid metal in the accommodation chamber 110 can easily pass through the valve structure 121, so that the liquid metal can flow into the capacitive sensor 122 more easily. When the accommodation chamber 110 is restored, the liquid metal flowing into the capacitive sensor 122 flows into the first conduit 1211 connected with the accommodation chamber 110 through the second conduit 1212, and then flows into the accommodation chamber 110.

The amount of liquid metal in the capacitive sensor 122 parallel to the stretching direction is less, and the amount of liquid metal in the capacitive sensor 122 perpendicular to the stretching direction is larger. Therefore, the capacitance value of the capacitive sensor 122 perpendicular to the stretching direction is high, while the capacitance sensor 122 parallel to the stretching direction has a high capacitance value. The capacitance sensor 122 in the stretching direction has a low capacitance, so the magnitude and direction of the force can be determined based on the capacitance.

The capacitive sensor 122 is a liquid metal layer injected between two flexible substrates, thereby preventing the two flexible substrates from sticking together during the preparation process. In another embodiment, capacitive sensor 122 includes an interdigital capacitance. The interdigital capacitor can be printed by 3D printing method. The interdigital capacitor is set on a flexible substrate and consists of a first electrode cavity 1221 and a second electrode cavity 1222 arranged in a cross. The number and spacing of the interdigital capacitor can be selected according to the sensitivity needs. A capacitance structure is formed between one electrode cavity 1221 and the second electrode cavity 1222 for inducing corresponding capacitance according to the liquid metal capacity. In another embodiment, the interdigital capacitor has a certain thickness. In this embodiment, the interdigital capacitor has a certain thickness, for example, 20 microns, to prevent the first electrode cavity 1221 and the second electrode cavity 1222 from adhering. The specific thickness of the interdigital capacitor can also be selected according to actual conditions, and is not specifically limited in this implementation.

In another embodiment, referring to FIG. 2 , the electrical signal measurement device 120 further includes a solid electrode. The solid electrode includes a first electrode 131 and a second electrode 132 ; the first electrode 131 is connected to the first electrode cavity 1221 , and the second electrode 132 Connected to the second electrode cavity 1222 for detecting the capacitance value of the capacitive sensor 122 . By connecting an electrical signal receiver to the solid electrode position, the capacitance value induced by each capacitor is measured, and the force direction and force magnitude of the flexible sensor are determined based on the measured capacitance value. The capacitive sensor 122 and the electrical signal receiver may be connected by solid metal wires or conductive polymers.

This application also provides a method for preparing a flexible sensor, as shown in Figure 7, including step S1 to step S3, wherein:

Step S1: Provide a flexible substrate mold, fill the flexible substrate mold with a flexible substrate precursor and solidify it to form a flexible substrate;

Step S2, prepare an accommodation cavity and at least two electrical signal measurement devices on the flexible substrate, and fill the accommodation cavity with a liquid conductive medium; the electrical signal measurement device includes a valve structure and a capacitance sensor, and the capacitance sensor The sensor is connected to the accommodation cavity through the valve structure, and the connection between any two of the electrical signal measuring devices and the accommodation cavity has an included angle;

Step S3: Encapsulate the liquid conductive medium to complete the preparation of the flexible sensor.

The method for preparing a flexible sensor provided by this embodiment is to prepare an accommodation cavity and a valve structure on a flexible substrate. The accommodation cavity is filled with a liquid conductive medium, and capacitive sensors are prepared in at least two directions of the accommodation cavity. Due to the fluidity of the liquid conductive medium, when there is an external force to squeeze it, different amounts of liquid conductive medium will flow into the capacitive sensors in different directions. The force direction and force size of the flexible sensor can then be determined based on the inflow amount of the liquid conductive medium.

In one embodiment, providing a flexible substrate mold, filling the flexible substrate mold with a flexible substrate precursor and solidifying it to form a flexible substrate includes:

providing a rigid substrate;

According to the corresponding shapes of the accommodation cavity and the electrical signal measurement device, print a first mold on one side of the rigid substrate and solidify it to obtain the flexible substrate mold;

The flexible substrate precursor is filled into the flexible substrate mold until it is filled and solidified to form the flexible substrate.

When printing a flexible substrate mold, the flexible substrate mold can be printed on the surface of the rigid substrate through 3D printing technology. The materials used to form the mold include polyvinyl chloride (PVC), polyamide PA, styrene terpolymer ABS, etc. The flexible substrate material can be polydimethylsiloxane (PDMS), polyimide (PI) and polyimide (PI). Methyl methacrylate PMMA, etc.

In one embodiment, preparing an accommodation cavity and at least two electrical signal measurement devices on the flexible substrate includes:

Print the accommodation cavity on the flexible substrate, and print the electrical signal measurement device in at least two directions of the accommodation cavity;

A liquid conductive medium is filled into the accommodation cavity, so that the surface of the liquid conductive medium is oxidized to form a fixed shape.

In this embodiment, 3D printing technology is used to first print the accommodation cavity on a flexible substrate, fill the accommodation cavity with liquid conductive medium, and then print multiple electrical signal measurement devices in different directions of the prepared accommodation cavity to complete the alignment. Preparation of accommodating cavity and electrical signal measuring device.

In one embodiment, preparing an accommodation cavity and at least two electrical signal measurement devices on the flexible substrate includes:

According to the corresponding shapes of the accommodation cavity and the electrical signal measurement device, print a second mold on the flexible substrate and/or the flexible substrate mold and solidify it;

Filling the second mold with the precursor liquid material until it is filled and solidified;

Remove the second mold located in the containing cavity and the electrical signal measuring device;

A liquid conductive medium is filled into the accommodation cavity, so that the surface of the liquid conductive medium is oxidized to form a fixed shape.

In this embodiment, when preparing the accommodation cavity and the electrical signal measurement device, first, a second mold is printed on the flexible substrate and/or the flexible substrate mold according to the shape of the accommodation cavity and the electrical signal measurement device, and the flexible substrate precursor is The body is filled into the second mold to prepare the containing cavity, valve structure and capacitive sensor. Since the hard mold material solidifies quickly and the structure is not easy to collapse, the three-dimensional structure of the accommodation cavity and electrical signal measurement device prepared using the hard mold is more accurate. In addition, the different size requirements of the accommodation cavity and electrical signal measurement device can be met by controlling the height of the mold, or by stacking and printing multi-layer molds. The material of the accommodation cavity and the valve structure can be the same as the flexible substrate material, such as polydimethylsiloxane PDMS, polyimide PI, polymethylmethacrylate PMMA, etc. The liquid conductive medium can be liquid metal. It should be noted that if there is only one layer of structure, there is no special requirement for the oxidation degree of the liquid metal; if a hard mold needs to be printed on the surface of the upper flexible substrate of the liquid metal, the oxidation degree is 1-3wt% liquid metal, that is, the ratio of gallium oxide to gallium is 1-3wt%. The liquid metal in this state is easy to form and can play a certain supporting role. The filling amount of the liquid conductive medium (the volume of the accommodation cavity) should be greater than or equal to the total volume of all capacitive sensors.

In one embodiment, referring to Figure 2, the electrical signal measurement device further includes a solid-state electrode, the solid-state electrode is connected to the capacitive sensor, and the solid-state electrode includes a first electrode and a second electrode;

Using 3D printing technology, the capacitive sensor 122 is printed in at least two directions of the accommodation cavity. The capacitive sensor 122 includes a first electrode cavity 1221 and a second electrode cavity 1222;

Using 3D printing technology, a layer of the liquid conductive medium is printed on the corresponding positions of the valve structure and the capacitive sensor;

The first electrode 131 is placed in the first electrode cavity 1221, and the second electrode 132 is placed in the second electrode cavity 1222.

Among them, the liquid conductive medium used in the above process can be liquid metal with an oxidation degree of 1.0wt%-3.0wt%, which is easier to form and can prevent the upper and lower flexible substrates from adhering during packaging; and has a better interface combination with the flexible substrate , good wettability. The solid electrode can be disposed near the valve structure 121. This arrangement can prevent the solid electrode from debonding from the flexible substrate during the stretching process.

In one embodiment, encapsulating the liquid conductive medium includes:

According to the corresponding shapes of the accommodation cavity and the electrical signal measurement device, print an upper mold on the flexible substrate mold and/or the flexible substrate and solidify it;

Fill the upper mold with the flexible substrate precursor until it is filled and solidified, so that the flexible substrate precursor coats the liquid conductive medium;

The flexible substrate mold and the upper mold are removed to obtain the flexible sensor.

Specifically, when encapsulating, the upper mold containing the cavity, the valve structure and the corresponding structure of the capacitive sensor is printed on the flexible substrate mold and/or the flexible substrate, and then the flexible substrate precursor is filled into the upper mold, so that The flexible substrate precursor is coated with a liquid conductive medium, and after solidification, an upper flexible substrate is formed to realize the packaging of the accommodation cavity, valve structure and capacitive sensor. In addition, after removing the second mold located in the accommodation cavity and the electrical signal measurement device, only the upper mold of the accommodation cavity, the valve structure and the corresponding structure of the capacitive sensor can be printed on the second mold outside the accommodation cavity, by filling the flexible liner. The bottom precursor completes the packaging. Of course, the second mold corresponding to the accommodation cavity and the electrical signal measurement device can also be removed. During packaging, the upper mold is printed on the flexible substrate mold, and the packaging is completed by filling the flexible substrate precursor. If there are special shape requirements for the prepared flexible sensor, a hard mold of the corresponding shape can be printed on the surface of the upper flexible substrate, and then the flexible substrate precursor can be filled in and solidified to form the corresponding shape.

Since the structures of flexible sensors used in different parts may be different, this application takes the preparation method of a flexible sensor with four electrical signal measuring devices for the knee area as an example to illustrate.

The preparation method of the flexible sensor specifically includes the following steps:

(1) Through 3D printing technology, use PVC material to print the first mold on the polylactic acid rigid substrate according to the corresponding shapes of the four electrical signal measurement devices 120 and one accommodation cavity 110 and solidify to obtain a flexible substrate mold. The first The height of the mold is 20mm.

(2) Fill the flexible substrate mold with the PDMS flexible substrate precursor liquid material until the flexible substrate mold is filled. Use the heating plate to heat to 80°C and heat for 20 minutes to complete solidification to form a PDMS flexible substrate.

(3) Use the PDMS flexible substrate precursor liquid material to prepare the accommodation cavity 110 with the support structure 111, the capacitive sensor 122, and the valve structure 121 corresponding to each capacitive sensor 122 through 3D printing on the PDMS flexible substrate and solidify it. . It is also possible to use PVC material to print a second mold on the PDMS flexible substrate and/or the flexible substrate mold according to the shapes of the accommodation cavity 110, the capacitive sensor 122 and the valve structure 121 and solidify it, and then fill the second mold with the PDMS flexible liner. After the bottom precursor liquid material is filled and solidified, the second mold corresponding to the shape of the containing cavity and the electrical signal measuring device is removed. The capacitive sensor 122 area is rectangular, 4cm×3cm. Four electrical signal measuring devices 120 form a cross shape; the accommodation cavity 110 is circular with a diameter of 7 cm.

(4) Fill the liquid conductive medium storage area of the accommodation cavity 110 with liquid metal EGaIn to naturally oxidize the surface of the liquid metal to form a fixed shape and fixed area.

(5) Use EGaIn with a high viscosity and an oxidation degree of 1.7wt% to print corresponding patterns according to the shapes of the valve structure 121 and the capacitive sensor 122 through a 3D printing method in the capacitive sensing area, with a thickness of 20 microns.

(6) Place a solid electrode near the valve structure 121. During stretching, the middle position deforms greatly and the two sides deform slightly to prevent the solid electrode from debonding from the flexible substrate during the stretching process.

(7) Print the upper mold on the flexible substrate mold, fill the liquid metal surface and solid electrode with the flexible substrate precursor liquid material again, and heat and solidify to complete the overall packaging of the flexible sensor.

(8) Remove the rigid substrate and upper mold, connect the solid electrode to the electrical signal receiver, and complete the preparation of the flexible sensor.

This application also provides a method of using the above-mentioned flexible sensor. As shown in Figure 8, the method of using the flexible sensor includes steps 810 to 830, wherein:

Step 810, place the accommodation cavity 110 of the flexible sensor on the surface of the object to be measured, and paste the multiple electrical signal measuring devices 120 on the surface of the object to be measured in different directions;

Step 820, obtain the parameters of each electrical signal measurement device 120;

Step 830: Determine the force direction and force magnitude on the surface of the object to be measured based on the parameters.

This application takes the previously prepared flexible sensor for the knee area as an example to illustrate its use. The accommodating cavity 110 of the prepared flexible sensor is placed on the surface of the body to be measured, and the measurement of human body motion signals specifically includes the following steps:

(1) Paste the two electrical signal measuring devices 120 of the flexible sensor to the knee parallel to the muscle stretching direction, and paste the other two electrical signal measuring devices 120 perpendicular to the muscle stretching direction on both sides of the knee. A point-type adhesive dressing is applied around the accommodation cavity 110 of the flexible sensor and on the electrical signal measuring device 120 to ensure that the extrusion process of the accommodation cavity 110 and the stretching process of the electrical signal measuring device 120 are relatively independent.

(2) When the knee bends, it will produce a squeezing effect on the accommodation cavity 110. At the same time, when the valve structure 121 parallel to the force direction is stretched longitudinally, the valve structure 121 closes, making it more difficult for liquid metal to flow into the electrical signal measurement device 120. When the valve structure 121 in the vertical and force-bearing directions is stretched laterally, the opening of the valve structure 121 expands, making it easier for liquid metal to flow into the electrical signal measuring device 120 . The amount of liquid metal pouring into the capacitive sensor 122 of the four electrical signal measuring devices 120 is different. The amount of liquid metal in the capacitive sensor 122 parallel to the stretching direction is smaller, and the amount of liquid metal in the capacitive sensor 122 perpendicular to the stretching direction is smaller. Therefore, the capacitance value of the vertical capacitance sensor 122 is high, while the capacitance value of the parallel capacitance sensor 122 is low. Therefore, it is determined that the motion state of the knee is bent. The greater the difference between the two capacitance values, the greater the degree of knee bending. The motion status of the knee is inferred from the difference in electrical signals.

(3) When the liquid conductive medium storage area is restored, due to the action of the valve structure 121, the liquid metal easily flows out of the electrical signal measuring device 120 and returns to the containing cavity 110.

(4) Repeat the above cyclic actions to complete the measurement of the knee motion status.

It should be understood that although various steps in the flowcharts of FIGS. 7 and 8 are shown in sequence as indicated by arrows, these steps are not necessarily executed in the order indicated by arrows. Unless explicitly stated in this article, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in Figures 7 and 8 may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but may be executed at different times. These sub-steps or The execution order of the stages is not necessarily sequential, but may be performed in turn or alternately with other steps or sub-steps of other steps or at least part of the stages.

The technical features of the above-described embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, All should be considered to be within the scope of this manual.

The above-mentioned embodiments only express several implementation modes of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims.

Claims (13)

1. A flexible sensor, characterized in that it includes a receiving cavity and at least two electrical signal measuring devices; wherein: The accommodation cavity is filled with liquid conductive medium; The electrical signal measurement device is connected to the accommodation cavity, and the connection between any two electrical signal measurement devices and the accommodation cavity has an included angle, so that the liquid conductive medium in the accommodation cavity is subjected to After filling each of the electrical signal measuring devices with pressure, detect the parameters of each of the electrical signal measuring devices, and determine the force direction and force magnitude of the flexible sensor according to the parameters; The electrical signal measurement device includes a valve structure and a capacitive sensor; the capacitive sensor includes a first electrode cavity and a second electrode cavity; the first electrode cavity and the second electrode cavity are spaced apart; the first electrode cavity and the second electrode cavity is respectively connected to the accommodation cavity through the valve structure, and is used to induce the corresponding capacitance according to the capacity of the liquid conductive medium entering the first electrode cavity and the second electrode cavity; the valve structure is used to sense the corresponding capacitance according to the capacity of the liquid conductive medium entering the first electrode cavity and the second electrode cavity. The magnitude and direction of the pressure is adjusted to adjust the valve opening; when the flexible sensor is under pressure, the liquid conductive medium in the accommodation cavity is filled into the first electrode cavity and the second electrode cavity through the valve structure. 2. The flexible sensor according to claim 1, wherein the electrical signal measurement device further includes a solid electrode, the solid electrode includes a first electrode and a second electrode; the first electrode and the first The electrode cavity is connected, and the second electrode is connected to the second electrode cavity for detecting the capacitance value of the capacitance sensor. 3. The flexible sensor according to claim 1, wherein the valve structure includes a first conduit and a second conduit that are sleeved; The first end of the first conduit is connected to the accommodation chamber, the first end of the second conduit is connected to the capacitive sensor, and the second end of the second conduit extends from the second end of the first conduit. into the first conduit and connect with it. 4. The flexible sensor of claim 1, wherein the capacitive sensor includes an interdigital capacitance. 5. The flexible sensor according to claim 1, wherein a plurality of support structures are provided in the accommodation cavity, and the support structures extend toward the electrical signal measuring device along the center of the accommodation cavity. 6. The flexible sensor according to claim 1, characterized in that the included angles between any two adjacent electrical signal measuring devices and the accommodation cavity are equal. 7. A method for preparing a flexible sensor, characterized in that the preparation method is used to prepare the flexible sensor according to any one of claims 1 to 6, and the method includes: S1: Provide a flexible substrate mold, fill the flexible substrate mold with a flexible substrate precursor and solidify it to form a flexible substrate; S2: Prepare an accommodation cavity and at least two electrical signal measurement devices on the flexible substrate, and fill the accommodation cavity with a liquid conductive medium; the electrical signal measurement device includes a valve structure and a capacitance sensor, and the capacitance sensor It is connected to the accommodation cavity through the valve structure, and the connection between any two electrical signal measuring devices and the accommodation cavity has an included angle; S3: Encapsulate the liquid conductive medium to complete the preparation of the flexible sensor. 8. The method for preparing a flexible sensor according to claim 7, wherein step S1 includes: providing a rigid substrate; According to the corresponding shapes of the accommodation cavity and the electrical signal measurement device, print a first mold on the surface of the rigid substrate and solidify it to obtain the flexible substrate mold; The flexible substrate precursor is filled into the flexible substrate mold until it is filled and solidified to form the flexible substrate. 9. The method for preparing a flexible sensor according to claim 7, wherein step S2 includes: Print the accommodation cavity on the flexible substrate, and print the electrical signal measurement device in at least two directions of the accommodation cavity; A liquid conductive medium is filled into the accommodation cavity, so that the surface of the liquid conductive medium is oxidized to form a fixed shape. 10. The method for preparing a flexible sensor according to claim 7, wherein step S2 includes: According to the corresponding shapes of the accommodation cavity and the electrical signal measurement device, print a second mold on the flexible substrate and/or the flexible substrate mold and solidify it; Filling the second mold with the precursor liquid material until it is filled and solidified; Remove the second mold located in the containing cavity and the electrical signal measuring device; A liquid conductive medium is filled into the accommodation cavity, so that the surface of the liquid conductive medium is oxidized to form a fixed shape. 11. The method of preparing a flexible sensor according to claim 7, wherein the electrical signal measurement device further includes a solid electrode, and the solid electrode is connected to the capacitive sensor. 12. The method for preparing a flexible sensor according to claim 7, wherein step S3 includes: According to the corresponding shapes of the accommodation cavity and the electrical signal measurement device, print an upper mold on the flexible substrate mold and/or the flexible substrate and solidify it; Fill the upper mold with the flexible substrate precursor until it is filled and solidified, so that the flexible substrate precursor coats the liquid conductive medium; The flexible substrate mold and the upper mold are removed to obtain the flexible sensor. 13. The method of using the flexible sensor according to any one of claims 1 to 6, characterized in that the method includes: Place the accommodation cavity of the flexible sensor on the surface of the object to be measured, and paste a plurality of the electrical signal measuring devices on the surface of the object to be measured in different directions; Obtain parameters of each electrical signal measurement device; The force direction and force magnitude on the surface of the object to be measured are determined based on the parameters.