A flexible, high-sensitivity pressure sensor and its detection method
By employing a microcavity-pyramid composite structure and signal processing methods, the problems of sensitivity degradation and signal resolution of flexible pressure sensors in deep-water environments have been solved, achieving high hydrostatic pressure tolerance and dynamic signal amplification, and providing an efficient and comfortable physiological and motion monitoring solution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-05-29
- Publication Date
- 2026-06-30
AI Technical Summary
Existing flexible pressure sensors are easily compacted in deep water with high static pressure, resulting in decreased sensitivity and difficulty in distinguishing between static and dynamic signals. Furthermore, rigid packaging affects flexibility and wearing comfort.
A microcavity-pyramid composite structure design is adopted, which combines flexible materials and signal processing algorithms to achieve mechanical buffering and dynamic signal amplification. It includes a microcavity support layer and a pyramid microstructure sensitive layer, and is combined with high-pass filtering and wavelet packet decomposition methods.
It maintains high sensitivity under deep water and high pressure, can effectively distinguish weak dynamic signals, has excellent flexibility and wearing comfort, and achieves accurate monitoring of physiological and motion signals.
Smart Images
Figure CN122306276A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of flexible electronics and wearable devices, and more specifically to a flexible, high-sensitivity pressure sensor and its detection method. Background Technology
[0002] With the increasing frequency of deep-sea scientific expeditions, diving training, and underwater operations, the need for real-time and continuous monitoring of divers' physiological parameters in underwater environments, such as heart rate, pulse, respiratory rate, and movement status, is becoming increasingly urgent. Flexible pressure sensors, due to their excellent flexibility and wearability, are widely used for detecting human physiological signals under normal pressure. However, in deep-water environments with high hydrostatic pressure (ranging from several meters to hundreds of meters, corresponding to hydrostatic pressures exceeding 1 MPa), existing flexible pressure sensors generally suffer from the following limitations:
[0003] 1. Sensitive layer is easily compacted: The huge uniform static pressure from the outside can cause irreversible collapse or compression of the microstructures inside the sensor used to improve sensitivity, such as microcones, micropillars, and micropores, leading to a sharp drop in sensor sensitivity or even failure.
[0004] 2. Difficulty in distinguishing between static and dynamic signals: The static base pressure generated by high hydrostatic pressure is much stronger than weak dynamic physiological signals such as pulse and respiration. Traditional sensors cannot effectively decouple the two, resulting in the dynamic signal being submerged.
[0005] 3. Rigid encapsulation sacrifices flexibility: To resist water pressure, existing technologies mostly use rigid metal shells or thick waterproof layers for encapsulation. This not only reduces the flexibility and skin conformity of the sensor, increasing wearing discomfort, but also causes signal response delay due to the damping effect of the encapsulation layer, making it difficult to capture weak physiological signals.
[0006] Therefore, there is an urgent need to develop a flexible sensor structure and corresponding signal processing method that can combine high hydrostatic pressure resistance and high dynamic signal sensitivity, so as to achieve accurate perception of weak physiological signals of the human body, such as pulse waves and motion status, in deep water environments. Summary of the Invention
[0007] The present invention aims to overcome the shortcomings of the prior art and provide a flexible pressure sensor and its detection method that can maintain high sensitivity in deep water high hydrostatic pressure environment and effectively distinguish weak dynamic pressure signals.
[0008] To achieve the above objectives, the first aspect of this invention provides a flexible pressure sensor that, through a unique "micro-cavity-pyramid" composite structure design, achieves mechanical buffering under hydrostatic pressure and stress concentration amplification of dynamic signals. The sensor includes:
[0009] The bottom electrode layer, made of a flexible conductive material, is used to collect and transmit electrical signals generated by pressure changes.
[0010] A microcavity support layer is stacked on top of the bottom electrode layer. This layer contains a regularly distributed array of sealed microcavities. These microcavities are designed to undergo reversible compression when the sensor is subjected to deep-water hydrostatic pressure, providing a buffer space for the upper structure and thus mitigating or even blocking the direct compaction effect of hydrostatic pressure on the sensitive layer.
[0011] A pyramidal microstructure sensitive layer is disposed above the microcavity support layer. This layer comprises an array of pyramids made of elastic material, with the tips of the pyramid array positioned opposite the upper wall of the microcavity below. When subjected to dynamic pressure (such as a pulse), localized stress concentration occurs at the tips of the pyramids, amplifying minute pressure fluctuations into significant changes in contact area or deformation.
[0012] The top electrode layer is disposed opposite to the bottom electrode layer, and the two together constitute a resistive or capacitive sensing structure.
[0013] An encapsulation layer, covering the outermost layer of the sensor, is made of a flexible waterproof material to achieve overall waterproof encapsulation of the sensor and ensure its comfortable fit against human skin.
[0014] Preferably, the diameter of the microcavity is 50–200 μm, the height is 30–100 μm, and the arrangement period of the microcavity array is 100–300 μm.
[0015] Preferably, the base width of the pyramid microstructure is 20–100 μm and the height is 20–80 μm, and the arrangement period of its array corresponds to the arrangement period of the microcavities, so as to ensure that the tip of each pyramid can be aligned with the central area of a microcavity.
[0016] Preferably, the flexible conductive material of the bottom electrode layer or top electrode layer is selected from Ag / PDMS composite conductive layer, MXene / PDMS conductive layer or ITO / PET conductive film.
[0017] Preferably, the encapsulation layer is made of fluorosilicone rubber, polyurethane (PU), or other polymer waterproof elastomer materials.
[0018] Preferably, the sensor maintains more than 60% of its sensitivity under normal pressure even under a hydrostatic pressure of 1 MPa.
[0019] Preferably, multiple flexible pressure sensors can form a sensor array for multi-point, synchronous signal detection of different parts of the human body.
[0020] Preferably, the sensor can be connected to a host computer via a wireless communication module to achieve real-time signal transmission and data analysis in deep-water environments.
[0021] The second aspect of this invention provides a method for detecting human signals in deep water based on the aforementioned flexible pressure sensor. The method includes the following steps: Step 1, attaching the sensor to a target detection site on the human body (such as the wrist, neck, or joint) and connecting it to a signal acquisition module via a flexible waterproof wire; Step 2, in a deep-water environment, using the sensor to collect pressure change signals caused by human physiology or movement in real time; Step 3, processing the collected raw signals using a signal processing module, specifically employing a high-pass filtering algorithm to filter out the DC component of hydrostatic pressure determined by water depth; Step 4, extracting the filtered dynamic pressure component and analyzing it to identify and monitor the corresponding human pulse waveform or motion signal, thereby achieving real-time monitoring of underwater physiological and movement states.
[0022] Preferably, the signal processing module in step 3 further employs a baseline compensation algorithm and a wavelet packet decomposition method to effectively separate and identify the pulse signal and motion signal from the complex dynamic signal.
[0023] Compared with existing technologies, the flexible pressure sensor and its detection method provided by this invention have the following outstanding features and significant advancements:
[0024] High hydrostatic pressure tolerance and sensitivity retention: This invention creatively constructs a pressure buffer structure by introducing a microcavity support layer beneath the sensitive layer. In deep-water environments, the enormous hydrostatic pressure first acts on the microcavity, causing it to compress and deform, thereby absorbing and bearing the majority of the static pressure load. This effectively protects the upper pyramidal microstructure sensitive layer from overall compaction. Experiments show that under a hydrostatic pressure of 1 MPa, the sensitivity of the sensor of this invention can still be maintained at more than 60% of that under normal pressure, while the sensitivity of traditional sensors without buffer structures is typically less than 10% of that under normal pressure.
[0025] Dynamic Signal Amplification and High-Resolution Detection Capability: Existing rigid packaging solutions struggle to capture weak dynamic signals due to damping effects. This invention leverages the stress concentration effect of the pyramid-shaped microstructure sensitive layer. When weak dynamic pressures such as pulses are applied to the sensor, localized stress concentration occurs at the contact interface at the pyramid tip, transforming minute pressure fluctuations into significant changes in contact area or deformation, thereby causing drastic alterations in the electrical signal. This "mechanical amplification" mechanism enables the sensor to clearly distinguish weak physiological signals such as heart rate and pulse waves even in deep-water, high-pressure environments, achieving a significantly better signal-to-noise ratio than traditional flexible sensors.
[0026] Excellent flexibility and wearing comfort: Existing pressure-resistant sensors mostly use rigid or semi-rigid packaging, sacrificing flexibility. This invention uses high-molecular elastomer materials such as PDMS and Ecoflex, supplemented by flexible waterproof packaging, giving the sensor excellent flexibility and tensile strength. It can perfectly conform to the curvature of human skin, and will not cause discomfort even when worn underwater for a long time, while ensuring stable and reliable signal acquisition.
[0027] Precise signal processing and information decoupling: Using specialized signal processing methods such as high-pass filtering, baseline compensation, and wavelet packet decomposition, this invention effectively separates static pressure signals caused by water depth from dynamic pressure signals caused by physiological / motional factors. It can further distinguish pulse waves and limb movements with different frequency characteristics, achieving precise perception and information decoupling of complex pressure fields in deep-water environments. Traditional sensors often struggle to effectively separate static and dynamic pressure signals under the same conditions.
[0028] In summary, this invention breaks through the application bottleneck of existing flexible pressure sensors in deep-water high hydrostatic pressure environments, and provides an efficient, sensitive and comfortable solution for wearable physiological and motion monitoring in deep-water environments. It has broad application prospects in fields such as diver health monitoring, underwater rescue, deep-sea operation safety early warning, and underwater human-machine interaction. Attached Figure Description
[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific implementation methods.
[0030] Figure 1 This is an exploded view of the overall structure of the flexible pressure sensor of the present invention.
[0031] Figure 2 This is a flowchart illustrating the fabrication process of the pyramid and microcavity structures of this invention.
[0032] Figure 3 This is a schematic diagram of the flexible pressure sensor of the present invention being worn underwater.
[0033] In the figure: bottom electrode layer 1; microcavity support layer 2; pyramid microstructure sensitive layer 3; top electrode layer 4; encapsulation layer 5. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it.
[0035] Example 1: Sensor Structure and Fabrication
[0036] This embodiment provides a method such as Figure 1The flexible pressure sensor shown has the following structure:
[0037] Bottom electrode layer: An Ag / PDMS composite conductive film is prepared by spin coating and curing processes.
[0038] Microcavity support layer: Located above the bottom electrode layer. In this embodiment, a sacrificial layer process is used, such as... Figure 3 As shown, a hemispherical closed microcavity with a diameter of 100 μm and a height of 50 μm was prepared, and the arrangement period of the cavity array was 150 μm.
[0039] The pyramid microstructure sensitive layer, located above the microcavity support layer, is made of PDMS material. The pyramid has a base width of 50 μm and a height of 40 μm, and its array arrangement period is consistent with that of the microcavity layer, ensuring that the tip of each pyramid is located at the top center of the corresponding cavity.
[0040] Top electrode layer: Also using Ag / PDMS composite conductive film, covering the pyramid microstructure layer.
[0041] Encapsulation layer: Flexible fluorosilicone rubber material is used to completely cover the entire sensor structure through impregnation or spraying processes to form a waterproof protective layer and bring out the electrode contacts.
[0042] Figure 2 The fabrication process of the microcavity and pyramid composite structure in this embodiment is shown:
[0043] (a) First, a solution of PS microspheres with a diameter of a is drop-coated onto a clean glass substrate.
[0044] (b) By heating and evaporating the solvent, the PS microspheres are self-assembled and arranged on a glass plate.
[0045] (c) Next, PS microsphere solutions with diameters of b and c are added dropwise and the above steps are repeated to construct sacrificial templates with multiple layers or specific morphologies.
[0046] (d) Pour a mixture of PDMS precursor containing carbon black (CB) onto the prepared PS microsphere template.
[0047] (e) A mold with an array of pyramidal microstructures, which can be prepared by photolithography and etching of a silicon wafer, is aligned and coated onto a PDMS mixture.
[0048] (f) After heat curing, the PDMS / CB composite layer is peeled off from the template. After demolding, a composite functional layer with microcavities and corresponding pyramid structures is obtained.
[0049] Example 2: Underwater Signal Detection Application
[0050] like Figure 3 As shown, the sensor prepared according to the method in Example 1 is attached to the radial artery of the diver's wrist and connected to a signal acquisition and processing module located inside the waterproof chamber via a flexible waterproof wire. The diver descends from the surface to a depth of 30 meters, corresponding to a hydrostatic pressure of approximately 0.4 MPa, and performs hand flexion and extension movements at this depth.
[0051] The signal processing module first performs a high-pass filter on the acquired raw pressure signal, with a cutoff frequency set to 0.1 Hz, successfully filtering out the slowly changing hydrostatic pressure baseline caused by water depth variations. Subsequently, the extracted dynamic signals are analyzed. The results show that under a hydrostatic pressure of 0.4 MPa, the sensor can still clearly distinguish the pulse wave waveform synchronized with the heart rate, with a frequency of approximately 1 Hz and minimal signal amplitude attenuation. Simultaneously, larger amplitude, lower frequency motion signals caused by hand bending and extension can also be accurately identified. This demonstrates that the sensor of this invention possesses excellent dynamic signal detection capabilities in deep-water, high-pressure environments.
[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A flexible high-sensitivity pressure sensor, characterized by, include: The bottom electrode layer, used to collect pressure signals, is made of a flexible conductive material; The microcavity support layer is attached to the upper surface of the bottom electrode layer. Inside, there is a regularly distributed array of sealed, elastically compressible microcavities to provide a buffer space under deep water hydrostatic pressure. The pyramid microstructure sensitive layer is attached to the upper surface of the microcavity support layer, with the tip of each pyramid facing the central area of a microcavity below, in order to achieve the local stress concentration amplification effect. The top electrode layer forms a resistive or capacitive sensing structure with the bottom electrode layer. The encapsulation layer, covering the outermost layer, is made of flexible waterproof material to achieve waterproof protection and skin adhesion.
2. The flexible high-sensitivity pressure sensor according to claim 1, wherein, The microcavities have a diameter of 50–200 μm and a height of 30–100 μm, and the arrangement period of the microcavity array is 100–300 μm.
3. The flexible high-sensitivity pressure sensor according to claim 1, characterized in that, The base width of the pyramid microstructure is 20–100 μm, and the height is 20–80 μm. The pyramid spacing corresponds to the period of the microcavity.
4. The flexible high-sensitivity pressure sensor according to claim 1, characterized in that, The pyramid microstructure includes a first-size pyramid and a second-size pyramid, which are periodically distributed in alternation or row-column intervals to form a composite sensitive array.
5. The flexible high-sensitivity pressure sensor according to any one of claims 1 to 3, characterized in that, The flexible conductive material is an Ag / PDMS composite conductive layer, an MXene / PDMS conductive layer, or an ITO / PET conductive film.
6. The flexible high-sensitivity pressure sensor according to claim 1, characterized in that, The encapsulation layer is made of fluorosilicone rubber, polyurethane (PU), or other polymer waterproof elastomer materials.
7. The flexible high-sensitivity pressure sensor according to any one of claims 1 to 6, characterized in that, The sensor maintains over 60% of its normal pressure sensitivity under conditions of 25°C, 1MPa uniform hydrostatic pressure, and vertical pressure application.
8. The flexible high-sensitivity pressure sensor according to claim 1, characterized in that, Multiple sensors are arranged in a matrix to form an array, which is used to simultaneously detect physiological signals or motion states of the human body at different points.
9. The flexible high-sensitivity pressure sensor according to any one of claims 1 to 7, characterized in that, The sensor is connected to the host computer via a waterproof wireless communication module to achieve real-time signal transmission and data analysis in deep water.
10. A method for detecting human body signals in deep water based on a flexible, high-sensitivity pressure sensor according to any one of claims 1 to 9, characterized in that, Includes the following steps: (1) Attach the sensor to the wrist, neck or joint of the human body and connect it to the signal acquisition module through a waterproof flexible wire; (2) In deep water environments with a water depth ≥3m and a hydrostatic pressure ≥0.3MPa, real-time acquisition of raw pressure change signals; (3) The signal processing module uses a high-pass filter with a cutoff frequency of 0.05 to 0.2 Hz to filter out the DC component of hydrostatic pressure; (4) The baseline compensation algorithm and wavelet packet decomposition method are used to extract dynamic pressure components, identify pulse signals or motion signals, and realize underwater physiological and motion monitoring. The signal processing module employs a baseline compensation algorithm and wavelet packet decomposition method to distinguish between pulse signals and motion signals.