A liquid metal based flexible sensor structure and methods of use thereof

Abstract

The application discloses a flexible sensor structure based on liquid metal and a use method thereof, and relates to the technical field of pressure flexible sensor design, wherein the structure of the flexible sensor based on liquid metal comprises a flexible fiber inner tube, a plurality of flexible fiber outer tubes which are respectively surrounded on the periphery of the flexible fiber inner tube, and liquid metal which is filled in the flexible fiber inner tube and the flexible fiber outer tubes; when the pressure on any one of the flexible fiber outer tubes or the flexible fiber inner tube changes, the position of pressure and the pressure size are determined according to the position of the change of the resistance of the liquid metal in the flexible fiber outer tube or the flexible fiber inner tube and the size of the resistance change amount. The flexible sensor structure based on liquid metal provided in the application can still be used when part of the flexible fiber outer tubes in the plurality of flexible fiber outer tubes are damaged and liquid metal leaks, and the position of damage can be quickly located.

Description

Technical Field

[0001] This invention relates to the field of pressure and temperature flexible sensor design technology, specifically to a flexible sensor structure based on liquid metal and its usage method. Background Technology

[0002] Flexible electronics can be broadly defined as an emerging electronic technology that fabricates electronic devices made of organic / inorganic materials on flexible / ductile plastic or thin metal substrates. With its unique flexibility / ductility and efficient, low-cost manufacturing processes, it has broad application prospects in information, energy, medical, and defense fields, such as flexible electronic displays, organic light-emitting diodes (OLEDs), printing, thin-film solar panels, and surface mount technology (SMT) for electronics. Flexible electronics encompasses organic electronics, plastic electronics, bioelectronics, nanoelectronics, and printed electronics, including RFID, flexible displays, organic electroluminescent displays and lighting, chemical and biological sensors, flexible photovoltaics, flexible logic and storage, flexible batteries, and wearable devices. Among these, the development of flexible sensors based on organic metals is of great significance in the field of flexible electronics.

[0003] Traditional flexible sensors based on liquid metals involve injecting a low-melting-point alloy (such as gallium indium tin alloy, with a melting point of 6-24°C) into a microchannel. When the pressure on the flexible sensor changes, the cross-section of the microchannel at the point of pressure change alters, resulting in a change in impedance at that location. By using time-domain reflectometry (TDR) to emit ultrafast pulses to the flexible sensor, the pressure value and location of the pressure can be calculated based on the echo information.

[0004] However, traditional flexible sensors based on liquid metal often employ a single-tube structure or are laid out by impregnating the liquid metal into flexible fibers. When using a single-tube flexible sensor, if the single tube structure breaks, causing the liquid metal to leak, the damaged flexible sensor becomes unusable, and it is difficult to locate the breakage. When manufacturing flexible sensors by impregnating them with liquid metal into flexible fibers, the manufacturing cost is too high, and the process of impregnating the flexible fibers with liquid metal can easily damage the structural integrity of the flexible fiber (composite material). Summary of the Invention

[0005] This invention proposes a flexible sensor structure based on liquid metal and its usage method. After the flexible sensor based on liquid metal proposed in this invention is damaged, the location of the damage can be quickly located, and the sensor can still be used even when a part of the flexible sensor is damaged.

[0006] This invention provides a flexible sensor structure based on liquid metal, comprising:

[0007] Flexible fiber inner tube;

[0008] Multiple flexible fiber outer tubes surround the outer periphery of the flexible fiber inner tube;

[0009] Both the inner and outer flexible fiber tubes are filled with liquid metal.

[0010] When the pressure on any of the flexible fiber outer tubes or the flexible fiber inner tubes changes, the cross-section of the flexible fiber outer tube or the flexible fiber inner tube at the point where the pressure changes changes, and the resistance of the liquid metal inside the flexible fiber outer tube or the flexible fiber inner tube at the point where the pressure changes changes.

[0011] Based on the location and magnitude of the resistance change of the liquid metal inside the flexible fiber outer tube or the flexible fiber inner tube, the pressure location and pressure magnitude of the flexible fiber outer tube or the flexible fiber inner tube are determined.

[0012] Furthermore, the multiple flexible fiber outer tubes are distributed parallel to each other along the axial direction of the flexible fiber inner tube.

[0013] Furthermore, the multiple flexible fiber outer tubes are respectively surrounded by the flexible fiber inner tube in a stranded structure.

[0014] Furthermore, both the flexible fiber inner tube and the flexible fiber outer tube are made of SEBS thermoplastic elastic material.

[0015] Furthermore, the inner diameter of the flexible fiber inner tube is 50-500 micrometers, and the inner diameter of the flexible fiber outer tube is 10-200 micrometers.

[0016] This invention provides a method for using a flexible sensor structure based on liquid metal, comprising the following steps:

[0017] A high-voltage pulse signal is injected into the port of the flexible sensor, and the echo signal is received.

[0018] The received echo signal is solved using TDR (Time Domain Reflectometry) technology, and the pressure location and magnitude of some flexible fiber outer tubes are determined based on the impedance changes of the echo signal.

[0019] Furthermore, it also includes the following steps:

[0020] A set of Gaussian envelope modulated signals is injected into the port of the flexible sensor, and the echo signal is received.

[0021] By using pseudo-Wigner-Weil transform to solve the received echo signal, the characteristic feedback signals of the partially flexible fiber outer tube (2) at different pressure angles are obtained.

[0022] Furthermore, the expression formula for the Gaussian envelope modulation signal is as follows:

[0023]

[0024]

[0025]

[0026] Where S(t) represents the Gaussian incident signal;

[0027] α is a constant that determines the duration of the signal and decreases as the duration increases;

[0028] β is a constant, which controls the frequency bandwidth of the signal;

[0029] t, t0, and ω0 represent time, center time, and center frequency, respectively.

[0030] g(t) is the Gaussian envelope used to control the profile of the incident signal;

[0031] c(t) is a signal whose frequency increases linearly.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] The flexible sensor structure based on liquid metal provided in this invention specifically involves surrounding a flexible fiber inner tube with multiple flexible fiber outer tubes. This allows the flexible sensor to remain functional even when some of the outer tubes are damaged, resulting in liquid metal leakage, and enables rapid location of the damage. Furthermore, this invention discloses a method for using this flexible sensor. By transmitting a high-voltage pulse signal to the sensor's port and calculating the received echo signal using Time Domain Reflectometry (TDR), the pressure location and magnitude of the flexible sensor can be determined, along with the location of any damage. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 This is a side view schematic diagram of a flexible sensor structure based on liquid metal proposed in this invention;

[0036] Figure 2 This is a side view schematic diagram of a flexible sensor structure based on liquid metal proposed in this invention;

[0037] Figure 3 This is a three-dimensional structural diagram of a flexible sensor structure based on liquid metal proposed in this invention;

[0038] Figure 4 This is a three-dimensional structural diagram of a flexible sensor structure based on liquid metal proposed in this invention;

[0039] Figure 5 This is a schematic diagram of the micropores in the flexible tube in an embodiment of a flexible sensor structure based on liquid metal proposed in this invention;

[0040] Figure 6 This is a schematic diagram of the signal distribution calculated using time-domain reflectometry (TDR) technology in an embodiment of a flexible sensor structure based on liquid metal proposed in this invention.

[0041] Figure 7 This is a schematic diagram of the time-frequency domain solution after using the pseudo-Wigner-Weil transform in an embodiment of a flexible sensor structure based on liquid metal proposed in this invention. Detailed Implementation

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. However, it should be understood that the scope of protection of the present invention is not limited to the specific implementation.

[0043] Example 1

[0044] like Figure 1 As shown, the present invention provides a flexible sensor structure based on liquid metal, comprising:

[0045] Flexible fiber inner tube 1;

[0046] Multiple flexible fiber outer tubes 2 surround the outer periphery of the flexible fiber inner tube 1;

[0047] Both the flexible fiber inner tube 1 and the flexible fiber outer tube 2 are filled with liquid metal;

[0048] When the pressure on any of the flexible fiber outer tubes 2 or the flexible fiber inner tubes 1 changes, the cross-section of the flexible fiber outer tube 2 or the flexible fiber inner tube 1 at the point where the pressure changes changes, and the resistance of the liquid metal in the flexible fiber outer tube 2 or the flexible fiber inner tube 1 at the point where the pressure changes changes.

[0049] Based on the location and magnitude of the resistance change of the liquid metal in the flexible fiber outer tube 2 or the flexible fiber inner tube 1, the pressure location and pressure magnitude of the flexible fiber outer tube 2 or the flexible fiber inner tube 1 are determined.

[0050] The liquid metal-based flexible sensor structure provided by this invention includes a sensing core, namely a flexible fiber inner tube 1, and an outer sensing layer, namely multiple flexible fiber outer tubes 2 surrounding the flexible fiber inner tube 1. Both the flexible fiber inner tube 1 and the flexible fiber outer tubes 2 are filled with liquid metal. This sensor structure of the present invention has the following advantages:

[0051] Multiple flexible fiber outer tubes 2 located around the flexible fiber inner tube 1 can protect the flexible fiber inner tube 1, effectively preventing damage to the flexible fiber inner tube 1 to a certain extent. When only some of the flexible fiber outer tubes 2 are damaged, while the flexible fiber inner tube 1 is not damaged, the flexible sensor can still be used without affecting the overall performance.

[0052] like Figure 3 As shown, multiple flexible fiber outer tubes 2 are distributed parallel to each other along the axial direction of the flexible fiber inner tube 1. The multiple flexible fiber outer tubes 2 are distributed around the flexible fiber inner tube 1, so that the multiple flexible fiber outer tubes 2 form a protective barrier for the flexible fiber inner tube 1.

[0053] like Figure 4 As shown, multiple flexible fiber outer tubes 2 are respectively wrapped around the periphery of the flexible fiber inner tube 1 with a stranded structure. This is beneficial for ensuring that the multiple flexible fiber outer tubes 2 tightly surround the periphery of the flexible fiber inner tube 1.

[0054] like Figure 1-4 As shown, both the flexible fiber inner tube 1 and the flexible fiber outer tube 2 are made of SEBS thermoplastic elastic material.

[0055] like Figure 1-4 As shown, the inner diameter of the flexible fiber inner tube 1 is 50-500 micrometers, and the inner diameter of the flexible fiber outer tube 2 is 10-200 micrometers. The overall structure of the sensor in this invention is not too large, thereby expanding the application scenarios of this flexible sensor.

[0056] In the actual fabrication of the flexible sensor based on liquid metal in this invention, there are the following two methods:

[0057] Method 1:

[0058] Flexible fiber inner tube 1 was prepared using SEBS thermoplastic elastic material;

[0059] Multiple flexible fiber outer tubes were prepared using SEBS thermoplastic elastic material;

[0060] Liquid metal is injected into both the flexible fiber inner tube 1 and the multiple flexible fiber outer tubes 2;

[0061] Multiple flexible fiber outer tubes 2 are respectively surrounded and fixed to the periphery of the flexible fiber inner tube 1.

[0062] The structure of the liquid metal-based flexible sensor prepared according to the above steps is as follows: Figure 3 or Figure 4 As shown.

[0063] Method 2:

[0064] Thermoplastic elastic material is stretched into a flexible tube with multiple microstructures by using a hot drawing process. The multiple microstructures on the flexible tube are different microcavities, and the different microcavities form the cavities of the flexible fiber inner tube 1 and multiple flexible fiber outer tubes 2.

[0065] Liquid metal was injected into different micropores.

[0066] Different microporous structures on flexible tubes produced by hot drawing process, such as Figure 5 As shown, different micropores on the flexible tube form the cavities of the flexible fiber inner tube 1 and multiple flexible fiber outer tubes 2.

[0067] Example 2

[0068] like Figure 1 As shown, the present invention provides a method for using a flexible sensor structure based on liquid metal, comprising the following steps:

[0069] Step 1: Inject a high-voltage pulse signal into the port of the flexible sensor and receive the echo signal;

[0070] Step 2: Calculate the received echo signal using TDR (Time Domain Reflectometry) technology, and determine the pressure location and magnitude of the flexible fiber outer tube 2 based on the impedance change of the echo signal.

[0071] It also includes the following steps:

[0072] Step 3: Inject a set of Gaussian envelope modulated signals into the port of the flexible sensor and receive the echo signals;

[0073] Step 4: Use pseudo-Wigner-Weil transform to solve the received echo signal to obtain the characteristic feedback signals of the partially flexible fiber outer tube 2 at different pressure angles.

[0074] The formula for the Gaussian envelope modulation signal is:

[0075]

[0076]

[0077]

[0078] Where S(t) represents the Gaussian incident signal;

[0079] α is a constant that determines the duration of the signal and decreases as the duration increases;

[0080] β is a constant, which controls the frequency bandwidth of the signal;

[0081] t, t0, and ω0 represent time, center time, and center frequency, respectively.

[0082] g(t) is the Gaussian envelope used to control the profile of the incident signal;

[0083] c(t) is a signal whose frequency increases linearly.

[0084] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0085] 1. When using the liquid metal-based flexible sensor provided in this invention, a pulse signal with an ultrafast rise time (hundreds of picoseconds) is emitted to the port of the flexible sensor. The acquired echo signal is then processed using TDR (Time Domain Reflectometry) technology. The pressure location and magnitude of the sensor are determined based on the impedance change of the echo signal.

[0086] like Figure 6 As shown, Figure 6 The vertical axis represents the input voltage in volts, and the horizontal axis represents time in nanoseconds. Figure 6 middle:

[0087] At point A, the flexible sensor is homogeneous and not subjected to pressure.

[0088] The sharp increase in impedance at point B indicates that the sensor is under pressure. The pressure on the flexible sensor and the location of the pressure can be obtained by calculating the impedance and the time difference of the pulse input.

[0089] If the impedance drops sharply at point C, the liquid metal flexible sensor may be damaged.

[0090] The signal echo received at point D indicates that the pulse signal has reached the end of the sensor and returned.

[0091] 2. Time-frequency domain solution of flexible sensors:

[0092] By transmitting a set of Gaussian envelope modulated signals to the port of the flexible sensor, detecting the echo, and using the pseudo-Wigner-Weil transform to perform time-frequency domain calculations of the flexible sensor, such as... Figure 7 As shown, at this time, the pressure signals of the sensor at different angles can be detected.

[0093] When a portion of the multiple flexible fiber outer tubes 2 ruptures and leaks, a Gaussian signal is injected into the sensor, and the received signal is transformed using a pseudo-Wigner-Weil transform to obtain a characteristic feedback signal of the damage angle of the portion of the flexible fiber outer tube 2. For example... Figure 7 The damage feedback amplitude varies at different damage angles. The figure shows the damage signals at three angles: 90°, 180°, and 270°.

[0094] Finally, it should be noted that the above-disclosed embodiment is only one specific embodiment of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A flexible sensor structure based on liquid metal, characterized in that, include: Flexible fiber inner tube (1); Flexible fiber inner tube (1) is the sensing core; Multiple flexible fiber outer tubes (2) are distributed parallel to the axis of the flexible fiber inner tube (1) and are surrounded by the flexible fiber inner tube (1) with a stranded structure; the multiple flexible fiber outer tubes (2) are the outer sensing layer; The flexible fiber inner tube (1) and the flexible fiber outer tube (2) are both filled with liquid metal; When the pressure on any of the flexible fiber outer tubes (2) or the flexible fiber inner tubes (1) changes, the cross-section of the flexible fiber outer tube (2) or the flexible fiber inner tube (1) at the point where the pressure changes changes changes, and the resistance of the liquid metal in the flexible fiber outer tube (2) or the flexible fiber inner tube (1) at the point where the pressure changes changes changes; the location and magnitude of the resistance change of the liquid metal in the flexible fiber outer tube (2) or the flexible fiber inner tube (1) are calculated by using TDR time-domain reflectometry and pseudo-Wigner-Weil transform. Based on the location and magnitude of the change in resistance of the liquid metal in the flexible fiber outer tube (2) or the flexible fiber inner tube (1), the pressure location and pressure magnitude of the flexible fiber outer tube (2) or the flexible fiber inner tube (1) are determined. By transmitting a set of Gaussian envelope modulated signals to the port of the flexible sensor, detecting the echo, and using the pseudo-Wigner-Weil transform to perform time-frequency domain calculations on the flexible sensor, the pressure signals at different angles of the sensor can be detected. When a portion of the flexible fiber outer tubes (2) of the multiple flexible fiber outer tubes (2) is damaged and leaks, a Gaussian signal is injected into the flexible sensor, and the received signal is transformed by pseudo-Wigner-Weil to obtain the characteristic feedback signal of the damage angle of the portion of the flexible fiber outer tubes (2); the damage feedback amplitude is different for different damage angles.

2. The flexible sensor structure based on liquid metal according to claim 1, characterized in that: Both the flexible fiber inner tube (1) and the flexible fiber outer tube (2) are made of SEBS thermoplastic elastic material.

3. The flexible sensor structure based on liquid metal according to claim 1, characterized in that: The inner diameter of the flexible fiber inner tube (1) is 50-500 micrometers, and the inner diameter of the flexible fiber outer tube (2) is 10-200 micrometers.

4. A method of using a flexible sensor structure based on liquid metal according to any one of claims 1-3, characterized in that, Includes the following steps: A high-voltage pulse signal is injected into the port of the flexible sensor, and the echo signal is received. The received echo signal is solved using TDR time-domain reflectometry, and the pressure location and magnitude of the flexible fiber outer tube (2) are determined based on the impedance change of the echo signal.

5. The method of using the flexible sensor structure based on liquid metal according to claim 4, characterized in that, It also includes the following steps: A set of Gaussian envelope modulated signals is injected into the port of the flexible sensor, and the echo signal is received. By using pseudo-Wigner-Weil transform to solve the received echo signal, the characteristic feedback signals of the partially flexible fiber outer tube (2) at different pressure angles are obtained.

6. The method of using a flexible sensor structure based on liquid metal according to claim 5, characterized in that: The formula for expressing the Gaussian envelope modulated signal is: Where S(t) represents the Gaussian incident signal; α is a constant that determines the duration of the signal and decreases as the duration increases; β is a constant, which controls the frequency bandwidth of the signal; t, t0, and ω0 represent time, center time, and center frequency, respectively. g(t) is the Gaussian envelope used to control the profile of the incident signal; c(t) is a signal whose frequency increases linearly.

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