A mechanical and optical dual-modal sensor and intelligent detection method

Abstract

This invention provides a mechanical and optical dual-modal sensor and intelligent detection method. The technical solution involves separately mounting flexible photoelectric detection patches and flexible mechanical sensing patches on different flexible substrates, and introducing a high-stiffness optical window in the photoelectric measurement area to cut off the deformation transmission path and stabilize the optical path. Simultaneously, a time-series collaborative sampling mechanism under a unified time reference is introduced into the control and processing module to avoid the light source-driven transition edge of the mechanical signal sampling window. Furthermore, at the data processing level, an exponential compensation model based on the dynamic response characteristics of the physical system is established, and the steady-state value of the system is extracted by inverse fitting using unstable transient observation sequences, thereby reconstructing the true muscle force mechanical signal. This invention can solve the technical problems of mechanical deformation coupling and electromagnetic crosstalk between the photoelectric and mechanical modes in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of smart wearable sensor technology, specifically to a mechanical and optical dual-modal sensor and a smart detection method. Background Technology

[0002] With the development of flexible electronics technology, wearable sensing devices are widely used in motion analysis, medical health monitoring, and other fields. In complex human motion monitoring, single-modality sensors acquire limited information. For example, photoelectric sensors excel at extracting circulatory system information such as blood oxygenation and heart rate by continuously collecting photoplethysmography pulse waves, but they cannot reflect the force load on the limbs; mechanical sensors can accurately measure contact pressure and deformation, but they cannot reflect changes in cardiovascular function and blood oxygenation in the target area. Integrating these two technologies to achieve simultaneous acquisition of multi-dimensional physiological and physical information is an important direction for current industry development.

[0003] However, in existing flexible sensing integration solutions, photoelectric detection and mechanical sensing often struggle to achieve stable coordination on the same flexible platform, mainly due to the following technical bottlenecks: First, photoelectric detection requires extremely high geometric stability of the optical path between the light-emitting device and the detector, while mechanical sensing essentially relies on structural deformation caused by external forces. When these two types of sensors are integrated on the same flexible substrate, the deformation caused by the contraction of human muscles will inevitably be transmitted to the optical measurement area, causing optical path deflection or focal length changes, which in turn leads to severe optical motion artifacts.

[0004] Secondly, photoelectric sensing typically requires injecting a driving pulse current with large transient changes into the light-emitting unit, while the front end of flexible mechanical sensing often involves the measurement of weak signals with high impedance. If the system does not implement proper timing isolation, the electromagnetic noise generated by the transients of the light source driving will be directly coupled into the mechanical acquisition link, resulting in distortion of the mechanical signal waveform.

[0005] Therefore, how to develop a system-level integration solution for photoelectric detection and mechanical sensing on a flexible wearable platform is an urgent problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention proposes a mechanical and optical dual-modal sensor and intelligent detection method to solve the technical problems of mechanical deformation coupling and electromagnetic crosstalk between photoelectric and mechanical modes in existing technologies.

[0007] The technical solution adopted in this invention is to separately set the flexible photoelectric detection patch and the flexible mechanical sensing patch on different flexible substrates, and introduce a high-stiffness optical window in the photoelectric measurement area to cut off the deformation transmission path and stabilize the optical path; at the same time, a time-series collaborative sampling mechanism under a unified time reference is introduced in the control and processing module to avoid the light source-driven transition edge of the mechanical signal sampling window; further, at the data processing level, an exponential compensation model based on the dynamic response characteristics of the physical system is established, and the steady-state value of the system is extracted by inverse fitting using the unstable transient observation sequence, thereby restoring the real muscle force mechanical signal.

[0008] In a first possible implementation, a mechanical-optical dual-modal sensor is provided, comprising: Flexible photoelectric detection patches are used to collect photoelectric signals that reflect the optical characteristics of a target area; Flexible mechanical sensing patches are used to collect mechanical signals that reflect the force state of a target area; The control and processing module is electrically connected to the flexible photoelectric detection patch and the flexible mechanical sensing patch.

[0009] Furthermore, the flexible photoelectric detection patch and the flexible mechanical sensing patch are respectively disposed on different flexible substrates to prevent the deformation caused by the force sensing unit from being transmitted to the photoelectric measurement area.

[0010] Furthermore, the flexible photoelectric detection patch includes a light-emitting unit, a flexible photoelectric detection unit, an optical window, and a flexible photoelectric detection patch substrate; The light-emitting unit and the flexible photoelectric detection unit are arranged in parallel on the side of the flexible photoelectric detection patch substrate away from the target object to be tested. An optical window is provided between the flexible photoelectric detection patch substrate and the light-emitting unit and the flexible photoelectric detection unit, and the optical window is rigidly connected to the light-emitting unit and the flexible photoelectric detection unit respectively. The structural stiffness of the optical window is higher than that of the flexible photodetector patch substrate in the surrounding area, which is used to maintain the relative geometric position stability between the light-emitting unit and the flexible photodetector unit under the condition that the flexible photodetector patch substrate is bent and dynamically moved. The flexible photoelectric detection unit adopts a multi-layer thin film stacked structure, which can be an upright structure or an inverted structure. The upright structure, from top to bottom on the light-receiving surface, includes: a flexible transparent substrate, a hole transport layer, an active layer, an electron transport layer, and a metal electrode; The inverted structure, from top to bottom on the light-receiving surface, comprises: a flexible transparent substrate, an electron transport layer, an active layer, a hole transport layer, and a metal electrode.

[0011] Furthermore, the flexible mechanical sensing patch includes a force sensing unit and a flexible mechanical sensing patch substrate; The force sensing unit is disposed on the side of the flexible photoelectric detection patch substrate away from the target object; The force sensing unit adopts an upper and lower electrode structure or an in-plane interdigitated structure. The upper and lower electrode structure includes an upper electrode, a flexible force-sensitive layer, and a lower electrode stacked sequentially from top to bottom on the force-bearing surface; The in-plane interdigitated structure includes a flexible force-sensitive layer and flexible interdigitated electrodes stacked sequentially from top to bottom on the force-bearing surface.

[0012] Furthermore, the control processing module includes: The light source driving submodule is used to send periodic pulse-shaped light source driving signals to the light-emitting unit; The photoelectric sampling submodule is used to perform time-series collaborative sampling of optical signals based on a unified time reference. The optical signals include the acquisition of reflected optical signals from the target area during the period when the light-emitting unit is turned on, and the acquisition of ambient light baseline signals during the period when the light-emitting unit is turned off. The mechanical sampling submodule is used to acquire the mechanical signal output by the mechanical sensing patch. The sampling window of the mechanical signal is set within the time period after the state switching of the light-emitting unit is completed and the signal stabilizes. The data processing submodule is used to synchronously process the optical and mechanical signals to obtain the muscle oxygenation change characteristic signal and muscle force-related mechanical signal of the target area.

[0013] In conjunction with the first feasible approach, a second feasible approach provides an intelligent detection method that utilizes a mechanical and optical dual-modal sensor. The method includes the following steps: S1 sends a periodic pulse-shaped light source drive signal to the light-emitting unit of the flexible photodetector patch; S2 performs time-coordinated sampling of optical signals based on a unified time reference; The optical signals include: during the period when the light-emitting unit is turned on, acquiring the reflected optical signal reflected from the target area; and during the period when the light-emitting unit is turned off, acquiring the ambient light baseline signal. S3 acquires the mechanical signal output from the mechanical sensing patch; The sampling window for the mechanical signal is set within the time period after the state switching of the light-emitting unit is completed and the signal stabilizes; S4 performs synchronous processing on the optical and mechanical signals to obtain the muscle oxygenation change characteristic signal and muscle strength-related mechanical signal of the target area.

[0014] Furthermore, in step S4, the method for processing the acquired optical signal includes differential sampling processing, specifically including: The true light intensity of the target area is obtained by subtracting the reflected optical signal from the ambient light baseline signal.

[0015] Furthermore, the light-emitting unit includes at least two light sources of different wavelengths, and the specific process of acquiring the muscle oxygenation change characteristic signal of the target area includes: The light intensity at the initial moment under different wavelengths, and the light intensity at any moment, are obtained respectively. The formula for calculating the change in optical density at any given time relative to the initial time is: in, This represents the change in optical density. Indicates the initial time. Received light intensity, This represents the light intensity received at any time t; Based on the modified Lambert-Beer law, for any two wavelengths and Construct a system of simultaneous equations relating the change in optical density to the change in hemoglobin concentration: in, and They represent wavelengths of and The corresponding change in optical density, and These represent the wavelengths of deoxyhemoglobin. and The absorption coefficient at the bottom, and These represent the wavelengths of oxyhemoglobin. and The absorption coefficient at the bottom, and They represent wavelengths respectively. and The corresponding path correction factor, r, represents the physical distance between the light-emitting unit and the photodetector unit. This indicates the relative change in the concentration of deoxyhemoglobin. This indicates the relative change in the concentration of oxyhemoglobin. Solve the simultaneous equations to calculate the relative changes in the concentrations of deoxyhemoglobin and oxyhemoglobin, thereby obtaining the characteristics of muscle oxygenation changes in muscle tissue.

[0016] Furthermore, the specific process of acquiring muscle force-related mechanical signals in the target area includes: The force sensing unit acquires the corresponding mechanical signal generated by the deformation under force. The mechanical signal is converted into a deformation digital signal via analog-to-digital conversion. Based on the amplitude and periodic changes of the deformation digital signal, the contact pressure and deformation characteristics of the skeletal muscle in the target area during movement are mapped to obtain muscle force-related mechanical signals.

[0017] Furthermore, the synchronous processing of the acquired mechanical signals also includes dynamic compensation of the mechanical signals, specifically including the following steps: Obtain the observation sequence of the mechanical signal; Substituting the observation sequence and the initial observation values ​​into the following dynamic compensation model, the steady-state value of the system is extracted through time series fitting: in, This represents the observed value of the mechanical signal at time t in the observation sequence. The time constant of the flexible sensing system is derived from material physics parameters. , This represents the elastic stiffness coefficient of the flexible force-sensitive layer. This indicates the viscous damping system of the flexible force-sensitive layer. This represents the steady-state value of the system, i.e., the mechanical force after eliminating the viscoelastic delay of the material. This represents the initial observation value of the mechanical signal in the current stage. Indicates a time interval; The steady-state value of the system is used as the output of the actual muscle force-related mechanical signal of the skeletal muscle after dynamic compensation.

[0018] As can be seen from the above technical solution, the beneficial technical effects of the present invention are as follows: 1. By separating the heterogeneous substrate and introducing the optical window, the direct pulling of the photoelectric measurement area by skeletal muscle contraction deformation is avoided. Under the conditions of violent human movement and flexible bending, the relative geometric stability of the internal optical path is ensured, and optical motion artifacts are significantly reduced.

[0019] 2. By setting an interleaved timing-based collaborative sampling mechanism, the acquisition of weak mechanical signals precisely avoids electromagnetic interference caused by the transient drive of the light-emitting unit, ensuring the cleanliness and purity of the high-impedance mechanical signals and achieving synchronous and stable acquisition of dual-mode signals.

[0020] 3. A dynamic compensation model is introduced, which eliminates the need to wait for the flexible force-sensitive material to reach stability through creep. Instead, it directly extracts the steady-state mechanical force after eliminating the viscoelastic delay by extracting the transient observation sequence from the front end and performing algorithm calculations. This improves the real-time response and measurement accuracy of the system to transient muscle force exertion. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0022] Figure 1 This is a structural diagram of the device according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the flexible photoelectric detection patch and the flexible mechanical sensing patch disposed on the same substrate according to Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the photodetector measurement principle in Embodiment 1 of the present invention; Figure 4 This is a structural diagram of the flexible photoelectric detection unit according to Embodiment 1 of the present invention; Figure 5 This is a voltage-current density curve of the flexible photodetector of Embodiment 1 of the present invention under different power illumination at a wavelength of 635 nm. Figure 6 This is a structural diagram of the force sensing unit according to Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the force sensing unit measurement principle in Embodiment 1 of the present invention; Figure 8 This is a sensitivity curve of the force sensing unit under different pressures according to Embodiment 1 of the present invention; Figure 9 This is a flowchart of the method in Embodiment 2 of the present invention; Figure 10 This is a graph showing the test results of the subjects in Example 2 of the present invention. Detailed Implementation

[0023] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0024] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains. Example 1

[0025] This embodiment provides a mechanical and optical dual-mode sensor. The working principle of Embodiment 1 is explained in detail below: The device structure diagram of this embodiment is as follows: Figure 1 As shown, it includes: Flexible photoelectric detection patches are used to collect photoelectric signals that reflect the optical properties of the tested muscles.

[0026] Flexible mechanical sensing patches are used to collect mechanical signals that reflect the stress state of the tested muscles.

[0027] The control and processing module is electrically connected to the flexible photoelectric detection patch and the flexible mechanical sensing patch.

[0028] The flexible photoelectric detection patch and the flexible mechanical sensing patch are mechanically decoupled, so that the mechanical propagation path of the contact deformation generated by the flexible mechanical sensing patch is separated from the photoelectric measurement area of ​​the flexible photoelectric detection patch.

[0029] The control processing module is equipped with a timing-coordinated sampling mechanism based on a unified time reference to control the driving timing of the light-emitting unit and the synchronous acquisition of the photoelectric signal and the mechanical signal.

[0030] Flexible photoelectric detection patches and flexible mechanical sensing patches are respectively set on different flexible substrates to prevent the deformation caused by the force sensing unit from being transmitted to the photoelectric measurement area.

[0031] The flexible photoelectric detection patch, the flexible mechanical sensing patch, and the control processing module are electrically connected by flexible wires to ensure that when the force sensing unit undergoes mechanical deformation, the resulting deformation stress will not be transmitted to the optical measurement area of ​​the flexible photoelectric detection patch through the rigid connection.

[0032] Optionally, the flexible photoelectric detection patch and the flexible mechanical sensing patch are disposed on the same substrate, as shown in the schematic diagram below. Figure 2 As shown, a rigid mechanical isolation zone for cutting off stress is provided between the flexible photoelectric detection patch and the flexible mechanical sensing patch.

[0033] The flexible photodetector patch includes an optically stable structure and a flexible photodetector patch substrate. The optically stable structure includes a light-emitting unit (LED) and a flexible photodetector unit (OPD, organic photodiode).

[0034] A light-emitting unit and a flexible photodetector unit are arranged in parallel within an optically stabilized structure, which is positioned on the side of the flexible photodetector patch substrate furthest from the tested muscle. An optical window is provided between the flexible photodetector patch substrate and the optically stabilized structure, and this optical window is rigidly connected to both the light-emitting unit and the flexible photodetector unit. The light-emitting unit emits incident light into the target area through the optical window and receives reflected light through the flexible photodetector unit. The photodetector measurement principle diagram of this embodiment is shown below. Figure 3 As shown.

[0035] The structural stiffness of the optical window is higher than that of the flexible photodetector patch substrate in the surrounding area. This is used to maintain the relative geometric position stability between the light-emitting unit and the flexible photodetector unit under bending and dynamic movement conditions of the flexible photodetector patch substrate, thereby ensuring optical path stability.

[0036] In this embodiment, the flexible photodetector unit is a photodiode-type structure, employing a multilayer thin-film stacked structure. This multilayer thin-film stacked structure can be an upright or inverted structure, as shown in the structural diagram below. Figure 4 As shown: The upright structure, from top to bottom on the light-receiving surface (the side closest to the test muscle), comprises: a flexible transparent substrate, a hole transport layer, an active layer, an electron transport layer, and a metal electrode. The inverted structure, from top to bottom on the light-receiving surface, comprises: a flexible transparent substrate, an electron transport layer, an active layer, a hole transport layer, and a metal electrode.

[0037] Its material composition and specific preparation process are as follows: Flexible transparent substrate: A PEN / ITO composite conductive flexible substrate is used as the carrier layer and bottom electrode of the device.

[0038] Hole transport layer: PEDOT:PSS was used. The preparation process included: drawing a portion of the PEDOT:PSS solution with a syringe, then dripping the filtered solution onto the ITO substrate surface through a 0.45 µm PVDF needle filter, adjusting the spin coater speed to 6000 rpm, spin coating for 20 s, and then heat annealing at 150 ℃ for 10 minutes after spin coating to complete the preparation.

[0039] Active layer: Composed of a bulk heterojunction material consisting of donor PM6 and acceptor Y6.

[0040] The preparation process includes: mixing donor PM6 and acceptor Y6 at a mass ratio of 1:1.2 and dissolving them in chloroform solvent containing 0.5 vol% 1-chloronaphthalene to prepare a solution with a total concentration of 15 mg / mL; transferring the solution into a nitrogen-filled glove box and magnetically stirring at room temperature for 8 hours to ensure complete dissolution and mixing; then, in a nitrogen glove box, dynamically spin-coating the lower film surface at a speed of 2400 rpm for 30 seconds; after spin-coating, heat annealing at 100 °C for 3 minutes.

[0041] Electron transport layer: PDINN is used. The preparation process includes: dissolving PDINN in methanol to prepare a solution with a concentration of 2 mg / mL; placing the prepared active layer solution in a glove box filled with nitrogen and magnetically stirring for 8 hours to ensure uniform mixing; and then using a spin coater in the glove box to dynamically spin coat at a speed of 2000 rpm for 15 seconds.

[0042] Metal electrode: Silver is used. The fabrication process includes: placing the device into a vacuum deposition equipment through a specific mask, evacuating the internal environment to 2×10-4 Pa, first depositing a 10 nm Ag electrode at a rate of 0.8 Å / s, and then depositing a 90 nm Ag electrode at a rate of 2 Å / s.

[0043] To verify the performance of the flexible photoelectric detection unit prepared in this embodiment, its photoelectric characteristics were tested, such as... Figure 5 The figure shows the voltage-current density curves of the flexible photodetector in this embodiment under different power illumination at a wavelength of 635 nm. In the zero-bias (0 V) or low-bias operating range, the device exhibits extremely low dark current characteristics; simultaneously, as the incident light power (from 0 mW / cm²) increases... 2 Increased to 98.6 mW / cm 2 With the increase of ), the photocurrent density exhibits a significant and regular response change. This demonstrates that the flexible photodetector unit using this multilayer thin-film stacked structure possesses excellent weak light detection capability and photoelectric conversion efficiency, providing a solid hardware foundation for subsequent high signal-to-noise ratio muscle oxygen signal extraction.

[0044] In this embodiment, the flexible mechanical sensing patch further includes a force sensing unit and a flexible mechanical sensing patch substrate. The force sensing unit is disposed on the side of the flexible photoelectric detection patch substrate away from the tested muscle. The force sensing unit adopts an upper and lower electrode structure or an in-plane interdigitated structure, as shown in the structural diagram below. Figure 6 As shown in the diagram. During exercise, skeletal muscles generate mechanical output through contraction and relaxation, causing changes in the shape, volume, and surface force state of muscle tissue. These mechanical changes are transmitted to the muscle surface or adjacent areas, resulting in corresponding pressure, tension, or deformation on the muscle surface. By placing a force sensing module on or near the skeletal muscle surface, the mechanical forces generated during skeletal muscle movement can be acquired. The measurement principle diagram is shown in the diagram. Figure 7 As shown.

[0045] The upper and lower electrode structure consists of an upper electrode, a flexible force-sensitive layer, and a lower electrode stacked sequentially from top to bottom on the force-bearing surface (the side closest to the tested muscle).

[0046] The in-plane interdigitated structure includes a flexible force-sensitive layer and a flexible interdigitated electrode stacked sequentially from top to bottom on the force-bearing surface.

[0047] Its material composition and specific preparation process are as follows: Flexible interdigitated electrodes: Utilizes flexible FPC (flexible printed circuit board).

[0048] Flexible force-sensitive layer: a composite material of P(VDF-TrFE) nanofiber membrane and PVA / phosphate ion gel.

[0049] Its preparation process includes: 1 g of P(VDF-TrFE) powder was dissolved in a mixture of acetone and N,N-dimethylformamide (DMF) in a mass ratio of 1:1 (5 g:5 g). The solution was magnetically stirred at 70 °C for 4 hours until the P(VDF-TrFE) powder was completely dissolved to obtain a precursor solution for electrospinning.

[0050] After the precursor solution cooled to room temperature, the prepared solution was absorbed using a syringe for electrospinning. The voltage of the electrospinning equipment was set to 18 kV, and spinning was performed at a stable speed of 1 mL / h. The roller collection speed was set to 480 rpm. After electrospinning, the nanofiber membrane was placed in an electrically heated drying oven and annealed at 60 °C for 3 hours. 10 g of polyvinyl alcohol (PVA) was dissolved in 90 g of pure water, and the mixture was magnetically stirred at 90 °C for 3 hours until completely dissolved.

[0051] Once the PVA solution has cooled to room temperature, add 13.94 g of phosphoric acid and stir magnetically for 2 hours at room temperature until it is uniformly dispersed. Let the mixture stand for 2 hours until all air bubbles in the solution have completely disappeared, thus obtaining an ionogel solution.

[0052] Finally, a sample of the obtained P(VDF-TrFE) nanofiber membrane was taken and completely immersed in an ionomer gel solution. Once the P(VDF-TrFE) nanofiber membrane became transparent, it was laid flat on a flexible PET substrate and placed in a 40°C drying oven to cure and shape, thus obtaining the sensitive layer of the sensor. To verify the sensing performance of the force sensing unit prepared in this embodiment, a pressure response test was performed.

[0053] like Figure 8 The figure shows the sensitivity curves of the force sensing unit under different pressures in this embodiment. The relative capacitance change ((C-C0) / C0) of the force sensing unit increases significantly with the increase of the applied pressure, and it exhibits a piecewise high-sensitivity linear response in different pressure ranges. This wide-range and extremely high-sensitivity response characteristic proves that the force sensing unit can not only accurately capture weak muscle surface tremors, but also adapt to the monitoring of large muscle contraction forces during strenuous exercise.

[0054] In this embodiment, the control processing module further includes: a light source driving submodule, used to send a periodic pulse-shaped light source driving signal to the light-emitting unit; a photoelectric sampling submodule, used to perform time-sequential collaborative sampling of optical signals based on a unified time reference, the optical signals including the collected reflected optical signals of the target area during the light-emitting unit's on period and the collected ambient light baseline signal during the light-emitting unit's off period; a mechanical sampling submodule, used to acquire the mechanical signals output by the mechanical sensing patch, the sampling window of the mechanical signals being set within the time period after the light-emitting unit's state switching is completed and the signal stabilizes; and a data processing submodule, used to synchronously process the optical signals and mechanical signals to acquire the muscle oxygenation change characteristic signal and muscle strength-related mechanical signal of the target area.

[0055] The following are the substances corresponding to the English abbreviations: PEN / ITO: Polyethylene naphthalate / Indium tin oxide; PEDOT:PSS: Poly(3,4-ethylenedioxythiophene): Polystyrene sulfonate; PM6: A fluorinated benzodithiophene polymer donor material; Y6: A non-fullerene small molecule acceptor material with benzothiadiazole as its core; PDINN: a perylene diimide derivative; P(VDF-TrFE): Polyvinylidene fluoride-trifluoroethylene; PVA: Polyvinyl alcohol. Example 2

[0056] This embodiment provides an intelligent detection method for a mechanical and optical dual-modal sensor, applied to a mechanical and optical dual-modal sensor as described in Embodiment 1. The flowchart of this embodiment is as follows. Figure 9 As shown, it includes the following steps: S1 sends a periodic pulse-shaped light source drive signal to the light-emitting unit of the flexible photodetector patch; S2 performs time-coordinated sampling of optical signals based on a unified time reference; The optical signals include: during the period when the light-emitting unit is turned on, acquiring the reflected optical signal reflected from the target area; and during the period when the light-emitting unit is turned off, acquiring the ambient light baseline signal. S3 acquires the mechanical signal output from the mechanical sensing patch; The sampling window for the mechanical signal is set within the time period after the state switching of the light-emitting unit is completed and the signal stabilizes, so as to avoid electromagnetic interference generated by the transient of the light source driving on the high-impedance mechanical signal. S4 synchronously processes the acquired optical and mechanical signals to obtain the muscle oxygenation change characteristic signal and muscle strength-related mechanical signal of the target area.

[0057] In this embodiment, further, in step S4, the method for processing the acquired optical signal includes differential sampling processing, specifically including: The reflected optical signal is subtracted from the ambient light baseline signal to eliminate interference from ambient light and dark current, thereby obtaining the true light intensity of the target area.

[0058] In this embodiment, the light-emitting unit further includes at least two different wavelengths ( and The specific process of acquiring the characteristic signals of muscle oxygenation changes in the target area using a light source includes: When the oxygenation status of muscle tissue changes, the received reflected light signal changes accordingly. The working principle of muscle oxygenation monitoring is to use near-infrared spectroscopy to measure optical parameters within human tissues to obtain the tissue's oxygenation status. Different wavelengths of light have different absorption characteristics for oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb). The characteristic that light intensity gradually decreases with increasing optical path length during penetration can essentially be considered as the conversion of photon energy into heat energy. Light absorption is only related to the optical path length and the concentration of the medium, and can be described by the following formula: in, and These represent the outgoing light intensity and the incident light intensity, respectively. L represents the absorption coefficient of the medium, and L represents the optical path length.

[0059] The Lambert-Beer law is primarily used to characterize the attenuation of light intensity after passing through a medium. It quantitatively reflects the attenuation changes of near-infrared light after penetrating human tissue, and can be used to calculate hemoglobin concentration and blood oxygen saturation. This law states that when a beam of parallel monochromatic light passes through an absorbing solution, the absorbance of the solution is directly proportional to the optical path length and the solution concentration, defining optical density (OD). OD can then be represented as: Where L represents the optical path length of light through the solute. When the concentration of the absorber is low, the absorption coefficient is directly proportional to the concentration C of the substance: In the formula The extinction coefficient of an absorber depends only on the type of absorber and the wavelength of light. Therefore, optical density can be expressed as: Therefore, human tissue can be considered as a mixed solution with Hb and HbO2 as the main solutes. To determine the concentrations of the two substances, at least two different wavelengths of light are needed: in, and These represent two different wavelengths of light source. and These represent the wavelengths of deoxyhemoglobin. and The absorption coefficient is wavelength-dependent, and its specific value can be obtained by referring to a table. and Let represent the concentrations of Hb and HbO2, respectively, and r represent the distance between the light source and the detector. However, since human tissue is a strong scattering medium, light undergoes multiple scatterings and its direction of propagation changes continuously when propagating within the tissue. This results in the light's path being much longer than the distance between the light source and the detector. Delpy et al. proposed the modified Beer-Lambert law (MBLL), as shown in the following formula: DPF stands for Different Pathlength Factor, representing the ratio of the actual average optical path length to the source-detector distance. It is a parameter related to wavelength, measurement location, etc., and can be obtained by looking up a table. G is the attenuation factor, representing the light intensity attenuation caused by other tissues; this varies greatly between individuals and is difficult to determine definitively. It is difficult to determine the absolute amount of hemoglobin concentration using MBLL. When tissue blood oxygen parameters change, the attenuation of light by other tissues can be considered constant. Therefore, the initial time at different wavelengths is obtained separately. light intensity and the light intensity at any time t Calculate any time t relative to the initial time. The change in optical density is used to eliminate the effect of incident light intensity: in, This represents the change in optical density. This represents the light intensity received at the initial moment. This represents the light intensity received at any time t; Based on the modified Lambert-Beer law (MBLL), for any two wavelengths and Construct a system of simultaneous equations relating the change in optical density to the change in hemoglobin concentration: in, and They represent wavelengths of and The corresponding change in optical density, and These represent the wavelengths of deoxyhemoglobin. and The absorption coefficient at the bottom, and These represent the wavelengths of oxyhemoglobin. and The absorption coefficient at the bottom, and They represent wavelengths respectively. and The corresponding path correction factor, r, represents the physical distance between the light-emitting unit and the photodetector unit. This indicates the relative change in the concentration of deoxyhemoglobin. This indicates the relative change in the concentration of oxyhemoglobin.

[0060] Solve the system of simultaneous equations to calculate the relative change in the concentration of deoxyhemoglobin. The relative change in the concentration of oxyhemoglobin This allows for a comprehensive understanding of the characteristics of muscle tissue oxygenation changes.

[0061] In this embodiment, the specific process of acquiring the muscle force-related mechanical signals of the target area further includes: The force sensing unit generates corresponding mechanical signals by deforming under the action of skeletal muscle contraction and relaxation.

[0062] The mechanical signal is sequentially passed through an analog signal amplification circuit and a low-pass filter circuit to extract a high signal-to-noise ratio signal, and then converted into a deformation digital signal through analog-to-digital conversion; Based on the amplitude and periodic changes of the deformation digital signal, the contact pressure and deformation characteristics of the skeletal muscle in the target area during movement are mapped to obtain muscle force-related mechanical signals.

[0063] In this embodiment, furthermore, in order to eliminate the signal hysteresis error caused by the viscoelasticity of the flexible sensing patch, the synchronous processing of the acquired mechanical signal also includes dynamic compensation of the mechanical signal. Specific steps include: Obtain the observation sequence X(t) of the mechanical signals continuously acquired by the current mechanical sampling submodule; Substituting the observation sequence and the initial observation values ​​into the following dynamic compensation model, the steady-state value of the system is extracted through time series fitting: in, This represents the transient mechanical signal observation value measured by the force sensing unit at time t. The time constant of the flexible sensing system is derived from material physics parameters. , This represents the elastic stiffness coefficient of the flexible force-sensitive layer. This indicates the viscous damping system of the flexible force-sensitive layer. This represents the steady-state value of the system, i.e., the mechanical force after eliminating the material's viscoelastic delay, which is the steady-state value of the system's equilibrium as time approaches infinity. This represents the initial observation value of the mechanical signal in the current stage. Indicates a time interval; The steady-state value of the system is used as the output of the actual muscle force-related mechanical signal of the skeletal muscle after dynamic compensation.

[0064] Because the substrate materials of flexible mechanical sensing patches (including polymers such as silicone and polyurethane) generally exhibit viscoelastic characteristics, when skeletal muscle is subjected to transient mechanical impact or sustained contraction, the deformation and resistance / capacitance changes of the force sensing unit cannot instantly reach their maximum values. Instead, they exhibit a slow, creeping hysteresis. Directly reading the sensor data at the current moment will severely underestimate the true muscle force output.

[0065] To eliminate the dynamic delay error caused by the aforementioned material physical properties, this embodiment provides a first-order physical dynamic compensation algorithm based on lumped parameter analysis. By extracting transient ramp data at the initial stage of stress, the algorithm predicts and extracts the true steady-state stress value after the material has fully deformed. The specific physical modeling and derivation steps are detailed below: Establish a physical response model for the flexible force sensing unit: in, This represents the transient mechanical characteristics, contact pressure or deformation, measured by the force sensing unit at time t. This indicates the viscous damping system of the flexible force-sensitive layer. This represents the actual mechanical force exerted by the skeletal muscles in the target area. This indicates the internal resistance of the flexible force-sensitive layer as it tends to recover its initial state after being subjected to force; The The calculation formula is: in, This represents the elastic stiffness coefficient of the flexible force-sensitive layer. This represents the initial environmental reference value under no external force. This represents the transient mechanical characteristics measured by the force sensing unit at time t; Combining the above feedback terms, we construct the standard differential equation form: in, This represents the transient mechanical signal observation value, contact pressure, or deformation, measured by the force sensing unit at time t. This represents the elastic stiffness coefficient of the flexible force-sensitive layer. This indicates the viscous damping system of the flexible force-sensitive layer. This represents the actual mechanical force exerted by the skeletal muscles in the target area. This represents the initial environmental baseline value under no external force. For the step-force exertion or relaxation process of skeletal muscle during exercise, the actual mechanical force applied remains constant. That is, the actual mechanical force applied by the skeletal muscle in the target area is regarded as a constant step input, using the mechanical signal observation value at the initial moment of the current stage. Using these as initial conditions, the physical response model is integrally solved to obtain a dynamic compensation model describing the evolution of the mechanical signal over time: in, This represents the transient mechanical signal observation value measured by the force sensing unit at time t. The time constant of the flexible sensing system is derived from material physics parameters. , This represents the steady-state value of the system, i.e., the mechanical force after eliminating the material's viscoelastic delay, which is the steady-state value of the system's equilibrium as time approaches infinity. , This represents the observed mechanical signal value at the initial moment of the current stage. Indicates a time interval; In actual data processing implementation, the control unit does not need to calculate complex differential equations, but directly calls the derived exponential analytical solution model. The specific implementation logic is as follows: Obtain the observation sequence X(t) of the mechanical signals continuously acquired by the current mechanical sampling submodule; Substitute the observation sequence and the initial observation values ​​into the following dynamic compensation model, and extract the steady-state value of the system through time series fitting; The steady-state value of the system is used as the output of the actual muscle force-related mechanical signal of the skeletal muscle after dynamic compensation.

[0066] To verify the effectiveness of the method in practical applications, the sensor described in this application was used to perform in vivo dynamic motion monitoring of the forearm muscles of the subject, such as... Figure 10 The image shown depicts the test results for the test subjects.

[0067] Subjects donned the experimental equipment and sensors, then sat upright in a chair with their arms resting flat on a table. At the start of the experiment, subjects remained at rest for 15 seconds, recording initial grip strength and baseline muscle oxygenation levels. Subsequently, subjects maintained maximum grip strength and continued applying it until they could no longer hold the position. Throughout this process, grip strength signals were recorded in real-time using an ionization sensor, and muscle oxygenation signals were monitored in real-time using an OPD (Optical Displacement Device). The experimental equipment simultaneously acquired data and transmitted it to a computer in real-time. When a subject reached exhaustion, the time to exhaustion was immediately recorded. The subject then released the grip strength and rested until muscle oxygenation returned to normal levels, ending the experiment. In area a, subjects were at rest; in area b, subjects began the grip strength test; and in area c, subjects stopped the grip strength test and entered a resting state. The muscle strength and muscle oxygenation signals remained largely consistent throughout the testing phase. The muscle strength signal showed that the signal remained relatively stable at rest. After grip strength was initiated, the signal rapidly increased and remained at a high level, then gradually decreased as the duration of sustained contraction increased, rapidly returning to baseline at approximately 100 seconds, indicating the recovery phase after exhaustion. Correspondingly, muscle oxygenation signals showed only minor fluctuations at rest. However, during sustained gripping, ΔC(HbO2) gradually decreased, while ΔC(Hb) gradually increased, reaching its lowest and highest values ​​at approximately 100 seconds. The overall variation in ΔC(tHb) was relatively small, likely due to limited changes in local blood volume during the experiment; the main changes were reflected in the dynamic transition between hemoglobin oxygenation and deoxygenation. Further comparison revealed that when muscle strength maintained a high output, ΔC(HbO2) had already begun to decrease while ΔC(Hb) had continued to increase, indicating that the oxygen metabolic load within the muscle had gradually accumulated before muscle strength significantly decreased. As fatigue intensified, muscle strength signals gradually decreased, and the amplitude of muscle oxygenation signal fluctuations further increased, approaching extreme values ​​near the baseline when muscle strength dropped. Upon entering the recovery phase, muscle strength signals rapidly returned to baseline, while ΔC(HbO2) gradually increased and ΔC(Hb) gradually decreased, indicating that the local muscle oxygen metabolism began to recover after gripping ceased, but its recovery rate was slower than that of the mechanical output signal.

[0068] Test results clearly show that the method provided in this application effectively overcomes motion deformation and electromagnetic crosstalk, achieves high signal-to-noise ratio and synchronous and stable extraction of muscle mechanical signals and local blood oxygen metabolism signals, and clearly reflects the physiological synergistic relationship between muscle mechanical behavior and local blood oxygen consumption.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A mechanical and optical dual-mode sensor, characterized in that, include: Flexible photoelectric detection patches are used to collect photoelectric signals that reflect the optical characteristics of a target area; Flexible mechanical sensing patches are used to collect mechanical signals that reflect the force state of a target area; The control and processing module is electrically connected to the flexible photoelectric detection patch and the flexible mechanical sensing patch.

2. The mechanical and optical dual-mode sensor according to claim 1, wherein, The flexible photoelectric detection patch and the flexible mechanical sensing patch are respectively disposed on different flexible substrates to prevent the deformation caused by the force sensing unit from being transmitted to the photoelectric measurement area.

3. The mechanical and optical dual-mode sensor according to claim 1, characterized in that, The flexible photoelectric detection patch includes a light-emitting unit, a flexible photoelectric detection unit, an optical window, and a flexible photoelectric detection patch substrate; The light-emitting unit and the flexible photoelectric detection unit are arranged in parallel on the side of the flexible photoelectric detection patch substrate away from the target object to be tested. An optical window is provided between the flexible photoelectric detection patch substrate and the light-emitting unit and the flexible photoelectric detection unit, and the optical window is rigidly connected to the light-emitting unit and the flexible photoelectric detection unit respectively. The structural stiffness of the optical window is higher than that of the flexible photodetector patch substrate in the surrounding area, which is used to maintain the relative geometric position stability between the light-emitting unit and the flexible photodetector unit under the condition that the flexible photodetector patch substrate is bent and dynamically moved. The flexible photoelectric detection unit adopts a multi-layer thin film stacked structure, which can be an upright structure or an inverted structure. The upright structure, from top to bottom on the light-receiving surface, includes: a flexible transparent substrate, a hole transport layer, an active layer, an electron transport layer, and a metal electrode; The inverted structure, from top to bottom on the light-receiving surface, comprises: a flexible transparent substrate, an electron transport layer, an active layer, a hole transport layer, and a metal electrode.

4. The mechanical and optical dual-mode sensor according to claim 1, characterized in that, The flexible mechanical sensing patch includes a force sensing unit and a flexible mechanical sensing patch substrate; The force sensing unit is disposed on the side of the flexible photoelectric detection patch substrate away from the target object; The force sensing unit adopts an upper and lower electrode structure or an in-plane interdigitated structure. The upper and lower electrode structure includes an upper electrode, a flexible force-sensitive layer, and a lower electrode stacked sequentially from top to bottom on the force-bearing surface; The in-plane interdigitated structure includes a flexible force-sensitive layer and flexible interdigitated electrodes stacked sequentially from top to bottom on the force-bearing surface.

5. A mechanical and optical dual-modal sensor according to claim 3 or 4, characterized in that, The control processing module includes: The light source driving submodule is used to send periodic pulse-shaped light source driving signals to the light-emitting unit; The photoelectric sampling submodule is used to perform time-series collaborative sampling of optical signals based on a unified time reference. The optical signals include the acquisition of reflected optical signals from the target area during the period when the light-emitting unit is turned on, and the acquisition of ambient light baseline signals during the period when the light-emitting unit is turned off. The mechanical sampling submodule is used to acquire the mechanical signal output by the mechanical sensing patch. The sampling window of the mechanical signal is set within the time period after the state switching of the light-emitting unit is completed and the signal stabilizes. The data processing submodule is used to synchronously process the optical and mechanical signals to obtain the muscle oxygenation change characteristic signal and muscle force-related mechanical signal of the target area.

6. An intelligent detection method, characterized in that, The method, applied to a mechanical and optical dual-modal sensor as described in any one of claims 1 to 5, comprises the following steps: S1 sends periodic pulse-shaped light source drive signals to the light-emitting unit of the flexible photoelectric detection patch; S2 performs time-coordinated sampling of optical signals based on a unified time reference; The optical signals include: during the period when the light-emitting unit is turned on, acquiring the reflected optical signal reflected from the target area; and during the period when the light-emitting unit is turned off, acquiring the ambient light baseline signal. S3 acquires the mechanical signal output from the mechanical sensing patch; The sampling window for the mechanical signal is set within the time period after the state switching of the light-emitting unit is completed and the signal stabilizes; S4 performs synchronous processing on the optical and mechanical signals to obtain the muscle oxygenation change characteristic signal and muscle strength-related mechanical signal of the target area.

7. The method according to claim 6, characterized in that, In step S4, the method for processing the acquired optical signal includes differential sampling processing, specifically including: The true light intensity of the target area is obtained by subtracting the reflected optical signal from the ambient light baseline signal.

8. The method according to claim 7, characterized in that, The light-emitting unit includes at least two different wavelengths of light source, and the specific process of acquiring the muscle oxygenation change characteristic signal of the target area includes: The light intensity at the initial moment under different wavelengths, and the light intensity at any moment, are obtained respectively. The formula for calculating the change in optical density at any given time relative to the initial time is: in, This represents the change in optical density. Indicates the initial time. Received light intensity, This represents the light intensity received at any time t; Based on the modified Lambert-Beer law, for any two wavelengths and Construct a system of simultaneous equations relating the change in optical density to the change in hemoglobin concentration: in, and They represent wavelengths of and The corresponding change in optical density, and These represent the wavelengths of deoxyhemoglobin. and The absorption coefficient at the bottom, and These represent the wavelengths of oxyhemoglobin. and The absorption coefficient at the bottom, and They represent wavelengths respectively. and The corresponding path correction factor, r, represents the physical distance between the light-emitting unit and the photodetector unit. This indicates the relative change in the concentration of deoxyhemoglobin. This indicates the relative change in the concentration of oxyhemoglobin. Solve the simultaneous equations to calculate the relative changes in the concentrations of deoxyhemoglobin and oxyhemoglobin, thereby obtaining the characteristics of muscle oxygenation changes in muscle tissue.

9. The method according to claim 6, characterized in that, The specific process of obtaining muscle force-related mechanical signals of the target area includes: The force sensing unit acquires the corresponding mechanical signal generated by the deformation under force. The mechanical signal is converted into a deformation digital signal via analog-to-digital conversion. Based on the amplitude and periodic changes of the deformation digital signal, the contact pressure and deformation characteristics of the skeletal muscle in the target area during movement are mapped to obtain muscle force-related mechanical signals.

10. The method according to claim 6, characterized in that, The synchronous processing of the acquired mechanical signals also includes dynamic compensation of the mechanical signals, specifically including the following steps: Obtain the observation sequence of the mechanical signal; Substituting the observation sequence and the initial observation values ​​into the following dynamic compensation model, the steady-state value of the system is extracted through time series fitting: in, This represents the observed value of the mechanical signal at time t in the observation sequence. The time constant of the flexible sensing system is derived from material physics parameters. , This represents the elastic stiffness coefficient of the flexible force-sensitive layer. This represents the viscous damping system of the flexible force-sensitive layer. This represents the steady-state value of the system, i.e., the mechanical force after eliminating the viscoelastic delay of the material. This represents the initial observation value of the mechanical signal in the current stage. Indicates a time interval; The steady-state value of the system is used as the output of the actual muscle force-related mechanical signal of the skeletal muscle after dynamic compensation.

Images