A wearable flexible optical waveguide array sensing system and method

Abstract

This invention discloses a wearable flexible optical waveguide array sensing system and method, belonging to the field of respiratory monitoring technology. The wearable flexible optical waveguide array sensing system includes a flexible optical waveguide array sensing module attached to the surface of the user's chest and abdomen, and a signal acquisition and processing circuit electrically connected to the signal and power supply interface of the flexible optical waveguide array sensing module. The flexible optical waveguide array sensing module includes two oppositely arranged flexible circuit boards and a flexible optical medium layer disposed between the two flexible circuit boards. Each flexible circuit board has multiple optical sensing units arranged in an array. This invention adopts a multi-layer packaging design of flexible circuit boards, allowing direct attachment to the surface of the chest and abdomen for long-term wear without affecting the natural respiratory rhythm. The system has high integration, small size, low power consumption, high precision, anti-electromagnetic interference, and high real-time performance, making it suitable for use as a real-time sensing module in respiratory rehabilitation training and exoskeleton control.

Description

Technical Field

[0001] This invention relates to the field of respiratory monitoring technology, applicable to real-time control scenarios of respiratory exoskeletons, and particularly to a wearable flexible optical waveguide array sensing system. Background Technology

[0002] Respiratory rehabilitation training is a key means to improve lung ventilation and enhance respiratory muscle function, and it is widely used in clinical scenarios such as chronic obstructive pulmonary disease, neurogenic respiratory disorders, and postoperative respiratory function recovery. In recent years, respiratory exoskeletons, as a new type of rehabilitation assistive device, have brought hope for personalized and proactive rehabilitation training for patients by providing mechanical assistance to assist respiratory movements. Effective rehabilitation training requires precise differentiation and guidance of thoracic and abdominal breathing patterns, as they target different muscle groups such as the intercostal muscles and diaphragm, respectively, and are crucial for restoring respiratory coordination and efficiency. However, the effectiveness of respiratory exoskeletons is highly dependent on real-time and accurate perception of thoracic and abdominal respiratory movements.

[0003] Currently, most existing respiratory exoskeletons employ monitoring schemes based on single-point barometric pressure sensors or inertial measurement units. These technologies have significant limitations: First, their sensing area is limited, only acquiring localized information and failing to comprehensively capture the distributed deformation of the chest and abdominal surfaces. This makes it difficult to accurately reflect the spatial distribution differences in muscle activity under different breathing modes, resulting in insufficient ability to identify thoracic and abdominal breathing. Second, these sensors often suffer from response lag, and their signals are easily affected by changes in the user's posture and external interference, limiting monitoring accuracy and reliability. Furthermore, some devices use rigid sensors with poor fit, resulting in low comfort during long-term wear and making them unsuitable for daily or home rehabilitation environments.

[0004] Although some studies have explored the application of fiber optic sensing technology in respiratory monitoring, such as detecting surface undulations based on changes in light intensity or interference signals, existing solutions are mostly focused on static mattress monitoring or single-point measurements, lacking high-resolution array designs for wearable scenarios. At the same time, traditional fiber optic materials lack flexibility and have poor signal stability under dynamic bending conditions, failing to meet the urgent needs of respiratory rehabilitation exoskeletons for high comfort, high spatial resolution, and real-time pattern recognition.

[0005] Furthermore, existing respiratory exoskeleton systems often employ open-loop or simple closed-loop control strategies, relying heavily on single sensors or non-contact monitoring devices for sensor input. This makes it difficult to accurately capture and dynamically respond to the user's breathing intentions. Especially during rehabilitation training, patients exhibit diverse breathing patterns and poor chest-abdominal coordination. Traditional sensing systems often fail to distinguish between active and passive breathing in real time, leading to a disconnect between exoskeleton assistance and the user's breathing rhythm, and even "counter-breathing," which negatively impacts rehabilitation outcomes and user comfort. Moreover, existing wearable respiratory monitoring devices often use rigid circuit boards or encapsulation materials, which are difficult to adapt to the complex curved surfaces of the chest and abdomen. During user activity, these devices are prone to displacement, detachment, or pressure discomfort, affecting signal stability and user compliance. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the prior art by proposing a wearable flexible optical waveguide array sensing system and method. This system achieves real-time identification of muscle shape changes during respiration through array sensing, enabling continuous and stable monitoring of muscle deformation during the natural rise and fall of the chest and abdomen. It features high-precision muscle modeling, high real-time detection capability, strong anti-interference ability, and good wearability. This provides high-precision data support for respiratory rehabilitation training and a reliable basis for intelligent assistance adjustment and individualized assessment of exoskeletons.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A wearable flexible optical waveguide array sensing system includes a flexible optical waveguide array sensing module attached to the surface of the user's chest and abdomen, and further includes:

[0009] The signal acquisition and processing circuit is electrically connected to the signal and power supply interface of the flexible optical waveguide array sensing module, and is used to acquire and process the signals output by the flexible optical waveguide array sensing module.

[0010] The flexible optical waveguide array sensing module includes two oppositely arranged flexible circuit boards and a flexible optical medium layer disposed between the two flexible circuit boards. Each side of the flexible circuit board is provided with multiple optical sensing units arranged in an array.

[0011] Each optical sensing unit includes an emitter and a receiver symmetrically placed on a flexible circuit board to form a pair of independent optical channels. The flexible optical waveguide array sensing module senses the surface deformation of the chest and abdomen caused by respiration based on the dynamic fluctuations of light intensity measured by the optical sensing unit.

[0012] Preferably, the flexible optical medium layer has a multilayer structure, comprising:

[0013] The first flexible dielectric layer consists of two layers attached to the inner sides of the two flexible circuit boards;

[0014] A second flexible dielectric layer is disposed between two first flexible dielectric layers, and the refractive index of the second flexible dielectric layer is higher than that of the first flexible dielectric layers.

[0015] The second flexible dielectric layer and the first flexible dielectric layer together constitute a flexible refractive surface. When the deformation of the chest and abdomen surface causes the flexible optical dielectric layer to undergo micro-bending, stretching or compression deformation, the refraction path and transmission conditions of light in the flexible optical dielectric layer change, thereby causing a change in the light intensity received by the receiving electrode.

[0016] Preferably, the emitting electrode is an infrared light-emitting diode, and the receiving electrode is a photodiode.

[0017] Preferably, the optical path between the infrared light-emitting diode and the corresponding photodiode is 4mm to 6mm.

[0018] Preferably, the spacing between two adjacent optical sensing units is 6mm to 10mm.

[0019] Preferably, the overall size of the flexible optical waveguide array sensing module is 40mm x 40mm, and the optical sensing unit is integrated in 9 to 16 units.

[0020] Preferably, the signal acquisition and processing circuit includes:

[0021] The main control chip is used to synchronously sample and digitally filter signals from multiple optical channels, and convert the change in light intensity into the surface deformation of the chest and abdomen according to the preset light intensity-deformation mapping model.

[0022] A transimpedance amplifier is used to convert the photocurrent signal generated by the photodiode into a voltage signal and perform preliminary amplification.

[0023] The signal conditioning module is used to debias the amplified voltage signal and perform secondary amplification.

[0024] The filtering module is used to filter out high-frequency noise in the signal;

[0025] An analog-to-digital converter (ADC) is used to convert analog signals into digital signals.

[0026] Preferably, the wearable flexible optical waveguide array sensing system further includes a communication interface with the respiratory exoskeleton controller, used to transmit breathing pattern recognition results, chest and abdominal deformation, and respiratory rhythm parameters to the exoskeleton main control unit in real time. The main control chip supports multiple rehabilitation mode configurations, including:

[0027] Active Assist Mode: Adjusts the level of assistance based on real-time breathing intensity;

[0028] Pattern-guided mode: Guides patients to perform chest or abdominal breathing training;

[0029] Assessment and recording mode: Long-term recording of chest and abdominal movement data to generate rehabilitation reports;

[0030] The system can automatically or manually switch between the above modes according to different rehabilitation stages to achieve personalized rehabilitation training.

[0031] A method for using a wearable flexible optical waveguide array sensing system includes the following steps:

[0032] Select a flexible optical waveguide array sensing module of appropriate size based on the user's chest and abdominal circumference and attach it to the surface of the chest and abdominal cavity.

[0033] The signal acquisition and processing circuit acquires and processes the signal output by the flexible optical waveguide array sensing module, and then calculates the amplitude and phase difference of the light intensity change of each optical channel.

[0034] Respiratory type is determined based on amplitude and phase difference;

[0035] Based on the preset light intensity-deformation mapping model, the change in light intensity is converted into the surface deformation of the chest and abdomen in real time and displayed on the host computer in real time.

[0036] Preferably, the breathing type includes thoracic breathing, abdominal breathing, and mixed breathing.

[0037] Preferably, the flexible optical waveguide array sensing module covers the area of ​​respiratory muscle activity from the upper sternum to the upper umbilicus.

[0038] Compared with the prior art, the present invention provides a wearable flexible optical waveguide array sensing system and method, which has the following beneficial effects:

[0039] 1. In this invention, a micro-deformation modulation mechanism is achieved through each pair of ultra-short optical path infrared light-emitting diodes and photodiodes, as well as flexible optical waveguides. In each optical sensing unit, the light emitted by the infrared light-emitting diode is received by the photodiode over a short distance, resulting in minimal light energy attenuation. When the chest and abdomen undulate, causing micrometer-level bending or stretching of the flexible optical medium layer, the light transmission path is significantly disturbed, leading to a measurable and drastic change in light intensity. This direct conversion mechanism of "geometric deformation - light loss" eliminates the mechanical transmission or complex calculation process in traditional air pressure or inertial sensing, making the system extremely sensitive to subtle respiratory deformations with a response speed reaching the millisecond level. This allows for the capture of minute changes in breathing without delay, providing the possibility for accurate real-time control of the exoskeleton and solving the problems of lag and insufficient accuracy in existing technologies.

[0040] 2. In this invention, multiple optical sensing unit arrays are integrated on a flexible optical waveguide array sensing module and made to work independently and in parallel. The center-to-center distance between adjacent optical units in the array is short, which realizes high-density sampling of the surface deformation of the chest and abdomen. During breathing, different sensing units covering the thorax and abdomen will independently and synchronously record the local deformation signals of their respective areas. By analyzing the amplitude differences and phase relationships of these 16 optical channel signals, the signal processing system can accurately determine whether the thorax expansion is dominant (thoracic breathing) or the abdominal rise and fall is dominant (abdominal breathing), thus providing an unprecedented and quantifiable assessment basis for targeted rehabilitation training and solving the pattern recognition problem that single-point sensing cannot distinguish between thoracic and abdominal breathing.

[0041] 3. In this invention, the entire sensing module is based on a flexible circuit board and covered with a flexible optical medium layer. The material is soft and flexible, and can fit closely to the skin like a dressing. It deforms naturally with the muscles without causing any foreign body sensation. At the same time, optical waveguide sensing is a "contact shielded" measurement. The light signal is transmitted inside the medium and is not easily affected by common interference factors such as external ambient light, electromagnetic fields, or skin surface temperature and humidity. This physical characteristic ensures that the signal baseline is stable and the signal-to-noise ratio is high during long-term rehabilitation training. It avoids data interruption or distortion caused by wearing discomfort or signal drift, and solves the problems of poor fit and susceptibility to interference affecting long-term use of rigid sensors.

[0042] 4. In this invention, by highly integrating multiple pairs of optical sensing units, flexible waveguides, transimpedance amplifiers, filters, and main control chips into a thin and light module, the core sensing mechanism does not rely on large demodulators or complex optical paths, achieving system miniaturization and low power consumption. This allows the module to be directly used as an independent, plug-and-play sensing unit, seamlessly embedded in respiratory exoskeletons or smart clothing, providing the latter with stable and reliable real-time physiological signals. This greatly promotes the practical application of precision respiratory rehabilitation technology in clinical and home settings, and solves the problem that traditional fiber optic monitoring systems are bulky, complex, and difficult to use in wearable devices.

[0043] 5. This invention utilizes array-based high-density sensing and real-time pattern recognition algorithms to accurately distinguish between thoracic breathing, abdominal breathing, and mixed breathing in a wearable respiratory monitoring system. This allows the respiratory exoskeleton to switch assistance strategies based on real-time breathing types, enabling targeted training of different respiratory muscle groups. This significantly improves the accuracy and personalization of rehabilitation training, solving the problem of traditional single-point sensing's inability to identify breathing patterns. Simultaneously, the invention deeply integrates flexible optical waveguide sensing technology with the respiratory exoskeleton control system, forming an integrated intelligent rehabilitation solution encompassing "perception-recognition-control-assessment." It not only possesses high-sensitivity, high-spatial-resolution deformation detection capabilities but also serves as a "breathing intention decoder" for the exoskeleton, achieving natural breathing assistance through human-machine collaboration, thus promoting the development of respiratory rehabilitation equipment towards intelligence and personalization.

[0044] 6. This invention achieves truly "wearable" respiratory monitoring through a fully flexible, thin, and highly conforming modular design. The system not only possesses high-precision sensing capabilities but also significantly outperforms traditional rigid sensing devices in terms of wearing comfort, fit stability, and ease of use. The modules can be seamlessly integrated into everyday clothing, rehabilitation bandages, or exoskeleton structures, supporting long-term, dynamic, and natural respiratory monitoring. This provides a sustainable and highly compliant data collection method for respiratory rehabilitation training, promoting the extension of precision respiratory rehabilitation from clinical scenarios to home and daily settings. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structural layers of the flexible optical waveguide array sensing system of the present invention;

[0046] Figure 2 This is a schematic diagram of the planar structure of the optical sensing unit of the present invention;

[0047] Figure 3 This is a block diagram of the signal acquisition and processing circuit of the present invention;

[0048] Figure 4 A flowchart illustrating the method of using the wearable flexible optical waveguide array sensing system provided for the invention.

[0049] In the figure: 10, Flexible optical waveguide array sensing module; 110, Flexible circuit board; 120, Flexible optical dielectric layer; 121, First flexible dielectric layer; 122, Second flexible dielectric layer; 130, Optical sensing unit; 140, Signal and power supply interface; 20, Signal acquisition and processing circuit; 210, Main control chip; 220, Transimpedance amplifier; 230, Signal conditioning module; 240, Filtering module; 250, Analog-to-digital converter. Detailed Implementation

[0050] 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. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0051] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0052] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] like Figure 1 , Figure 2 , Figure 3 As shown, this embodiment proposes a wearable flexible optical waveguide array sensing system, including a flexible optical waveguide array sensing module 10 attached to the surface of the user's chest and abdomen. The flexible optical waveguide array sensing module 10 is used to sense the deformation of the chest and abdomen surface caused by breathing. Furthermore, the wearable flexible optical waveguide array sensing system also includes a signal acquisition and processing circuit 20. The signal acquisition and processing circuit 20 is electrically connected to the flexible optical waveguide array sensing module 10 through a wire. Specifically, a signal and power supply interface 140 is provided on the flexible optical waveguide array sensing module 10. The signal acquisition and processing circuit 20 can be connected to the flexible optical waveguide array sensing module 10 through the signal and power supply interface 140, thereby acquiring and processing the signals output by the flexible optical waveguide array sensing module 10.

[0054] The flexible optical waveguide array sensing module 10 includes a flexible circuit board 110 and a flexible optical medium layer 120. The two flexible circuit boards 110 are arranged opposite each other, with the two flexible circuit boards 110 on the outside, which serves as an encapsulation. The flexible optical medium layer 120 is disposed between the two flexible circuit boards 110, and multiple optical sensing units 130 arranged in an array are provided on each side of the flexible circuit board 110. In this way, the optical sensing units 130 are constructed based on the flexible circuit board 110 and the flexible optical medium layer 120, which gives the entire module good fit and comfort.

[0055] Specifically, the overall size of the flexible optical waveguide array sensing module 10 can be set to 40mm x 40mm, and the optical sensing unit 130 integrates 9 to 16 units. In this embodiment, the number of optical sensing units 130 is 16, which clarifies the high integration and compactness of the module. The main structure of the module consists of two flexible circuit boards 110 as the outer packaging and circuit carrier. The two flexible circuit boards 110 are placed opposite each other to form a packaging space.

[0056] It should be noted that the number of optical sensing units 130 is not limited to the aforementioned number. In practical applications, the number can be determined according to the resolution requirements. That is, more units can be integrated when high resolution is required, and fewer units can be integrated when low resolution is required. This embodiment is based on the muscle resolution size requirement, and sets up 16 optical sensing units 130 in a 4*4 arrangement.

[0057] The flexible optical medium layer 120 has a multilayer structure, including a first flexible medium layer 121 and a second flexible medium layer 122. The two first flexible medium layers 121 are arranged opposite each other and are attached to the inner sides of the two flexible circuit boards 110. The second flexible medium layer 122 is attached between the two first flexible medium layers 121. The refractive index of the second flexible medium layer is higher than that of the first flexible medium layer. Thus, the first flexible medium layer 121 in the flexible optical medium layer 120 is a low refractive index layer and the second flexible medium layer 122 is a high refractive index layer. The second flexible medium layer 122 and the first flexible medium layer 121 together constitute a flexible refractive surface. When the surface deformation of the chest and abdomen causes the flexible optical medium layer 120 to undergo micro-bending, stretching or compression deformation, the refraction path and transmission conditions of light in the flexible optical medium layer 120 change, thereby causing a change in the light intensity received by the optical sensing unit 130.

[0058] Furthermore, the flexible optical medium layer is made of silicone-based transparent elastomer material with an adjustable refractive index range of 1.41–1.48. By adjusting the refractive index difference between the first and second medium layers (Δn ≥ 0.05), efficient optical confinement and deformation-sensitive modulation are achieved. When the interface undergoes micro-bending deformation, the total internal reflection condition is disrupted, and the light energy leakage rate exhibits a nonlinear positive correlation with the curvature, thereby enabling high-sensitivity detection of millimeter-level deformations.

[0059] Before using the system, channel calibration is required: On a standard respiratory simulation platform, stepper motors are used to simulate chest and abdominal movements, recording the correspondence between light intensity changes and deformation in each channel, and establishing independent "light intensity-deformation" response curves for each channel. Calibration data is stored in the non-volatile memory of the main control chip for real-time signal processing.

[0060] Furthermore, among the multiple optical sensing units 130 arranged in an array, the spacing between two adjacent optical sensing units 130 is 6mm to 10mm. Specifically, in this embodiment, the spacing between two adjacent optical sensing units 130 is 8mm. This design determines the density of spatial sampling of chest and abdominal deformation by the system. It should be noted that this spacing is not limited to the aforementioned size. In the actual fabrication process, the aforementioned spacing size can be adjusted according to the resolution requirements.

[0061] Furthermore, multiple optical sensing units 130 are arranged in an array. Each optical sensing unit 130 includes an emitter and a corresponding receiver. The emitter and the corresponding receiver are symmetrically arranged on one side of the flexible circuit board 110. That is, both sides of the flexible circuit board 110 are provided with correspondingly distributed pairs of emitters and receivers. The number of optical sensing units 130 on each side of the flexible circuit board 110 is several. The emitter is an infrared light-emitting diode, and the receiver is a photodiode. Each infrared light-emitting diode and the corresponding photodiode are symmetrically arranged to form a pair of independent optical channels. In this embodiment, the optical path between the two is 4mm to 6mm. Specifically, in this embodiment, the optical path is 4mm. This ultra-short optical path is a key dimension to ensure a significant signal response to weak deformation.

[0062] Specifically, the signal acquisition and processing circuit 20 drives the infrared light-emitting diodes in each optical sensing unit 130 to emit light. The light enters the flexible optical medium layer 120, which is composed of the second flexible medium layer 122 and the first flexible medium layer 121. Since total internal reflection or refraction at a specific angle occurs when light travels from an optically dense medium (high refractive index layer) to an optically sparse medium (low refractive index layer), the light is effectively confined to propagate forward in the second flexible medium layer 122 and reaches the symmetrically arranged photodiodes via a short optical path of 4 mm. When the user's chest and abdomen rise and fall due to breathing, the force acts on the flexible optical waveguide array sensing module, causing the flexible optical medium layer 120 to undergo micro-bending, stretching, or compression deformation. This physical deformation directly changes the geometry and interface angle of the flexible refractive surface, thereby disturbing the transmission conditions of light within it. The direct result is that some of the light energy that was originally confined to the core layer will be refracted out from the interface due to the deformation, causing light transmission loss. The greater the deformation, the greater the light loss. In this way, the light intensity received by the photodiode at the end of each optical channel will be weakened by the above modulation process, and the photodiode will linearly convert this changing light intensity signal into a changing electrical signal (current signal) for output.

[0063] It should be noted that, due to the use of 16 independent optical sensing units 130 arranged in an array with a spacing of 8mm, the system can simultaneously acquire deformation signals of 16 different points within a 40mm x 40mm area on the surface of the chest and abdomen. The electrical signals of all these optical channels are transmitted in parallel to the signal acquisition and processing circuit 20 for processing, thereby reconstructing the dynamic deformation field of the chest and abdomen during breathing.

[0064] Meanwhile, the 16 optical sensing units arranged in an array enable the system to simultaneously monitor the deformation of multiple points within a 40mm x 40mm area, overcoming the limitations of single-point measurement. Furthermore, the 4mm optical path design for each optical channel results in an extremely short optical path and concentrated energy, making it highly sensitive to minute changes in optical loss caused by deformation, thus laying the structural foundation for high-sensitivity detection.

[0065] The second flexible dielectric layer 122 is sandwiched between the two first flexible dielectric layers 121 to form a multilayer flexible optical dielectric layer 120, forming a standard optical waveguide structure. This structure can not only efficiently transmit light from the infrared light-emitting diode to the photodiode, but also efficiently and predictably convert physical deformation (micro-bending, stretching, etc.) into changes in light intensity (i.e. signal modulation), ensuring the correctness of the sensing mechanism principle and the stability of the signal.

[0066] It is worth mentioning that the flexible optical waveguide array sensing module of this invention is specifically designed for wearable scenarios. Its overall structure is thin and flexible, with a thickness of only 4mm, allowing it to naturally bend with the curves of the human chest and abdomen without generating rebound stress. The module's edges are rounded and covered to avoid pressure or friction on the skin from sharp corners. In terms of wearing methods, the module can be fixed to the human body surface through one or more of the following methods:

[0067] 1. Medical-grade adhesive film bonding: The back of the module is pre-coated with medical-grade low-allergenic pressure-sensitive adhesive, which can be directly attached to a clean and dry skin surface, suitable for short-term high-precision monitoring scenarios;

[0068] 2. Elastic strap integration: The module can be embedded in elastic fabric straps or chest straps, achieving a stable fit through the uniform pressure of the straps, suitable for medium- and long-term rehabilitation training;

[0069] 3. Embedded integration of exoskeleton wearable structure: The module can be directly embedded into the chest and abdomen contact pads or the inner layer of the airbag of the respiratory exoskeleton, serving as the built-in sensing unit of the exoskeleton, realizing the integrated design of sensing and assistance.

[0070] All of the above wearing methods ensure that the module fits tightly to the skin and deforms synchronously with breathing, minimizing motion artifacts and signal drift.

[0071] like Figure 1 , Figure 2 and Figure 3 As shown, in a preferred embodiment, based on the above method, the signal acquisition and processing circuit 20 further includes a main control chip 210, a transimpedance amplifier 220, a signal conditioning module 230, a filtering module 240, and an analog-to-digital converter 250. The main control chip 210 is used to synchronously sample and perform IIR digital filtering on multi-channel signals, and convert the light intensity change into the chest and abdomen surface deformation according to the preset light intensity-deformation mapping model, and convert the abstract light intensity voltage value into the chest and abdomen surface deformation with physical meaning, thereby realizing the quantification of the signal. The transimpedance amplifier 220 is used to convert the photocurrent signal generated by the photodiode into a voltage signal and perform preliminary amplification. The signal conditioning module 230 is used to perform debiasing processing and secondary amplification on the amplified voltage signal. Through the two-stage amplification and conditioning of the transimpedance amplifier 220 and the signal conditioning module 230, the amplitude of the weak photocurrent signal is effectively improved and DC drift is eliminated.

[0072] The filtering module 240 is used to filter out high-frequency noise in the signal. The filtering module 240 includes a first-stage low-pass filter and a second-stage low-pass filter. Its cutoff frequency is set to 5Hz. This specific frequency value is set based on the physiological characteristic that the frequency of human respiratory movements is usually below 2Hz. It aims to retain the effective respiratory signal frequency band to the maximum extent, while powerfully filtering out high-frequency muscle tremors, power frequency interference and other noise, ensuring that the output signal has an extremely high signal-to-noise ratio.

[0073] The analog-to-digital converter 250 is used to convert analog signals into digital signals.

[0074] This approach utilizes analog-digital collaborative filtering and multi-channel synchronous acquisition, employing a sliding rheostat to achieve independent calibration of a single channel and synchronous acquisition of multiple channels. Simultaneously, it integrates a high-density infrared light-emitting diode (LED) – photodiode (PD) array with a flexible circuit board to achieve real-time multi-point distributed sensing.

[0075] In operation, the weak photocurrent signal output by the photodiode is first input to the transimpedance amplifier 220, which converts it into a voltage signal and performs preliminary amplification to boost the signal level for subsequent processing. The pre-amplified voltage signal is then sent to the signal conditioning module 230 for debiasing (eliminating DC bias voltage) and secondary amplification to further optimize signal quality. Subsequently, the signal enters the filtering module 240, where it passes through a first-stage and second-stage low-pass filter with a cutoff frequency of 5Hz to filter out all high-frequency noise above 5Hz, retaining the clean low-frequency analog signal containing the main breathing frequency band information. The purified analog signal is then converted into a digital signal by the analog-to-digital converter 250, and the digital signal is sent to the main control chip. The chip 210 first synchronously samples signals from 16 optical channels to ensure data alignment, then applies IIR digital filtering for final signal smoothing and baseline stabilization. The main control chip 210 calls a preset light intensity-deformation mapping model to convert the digital signal (representing light intensity) of each optical channel into the corresponding deformation in real time. The chip then continuously analyzes this deformation data at a rate of 100Hz, calculating the average amplitude of each channel signal in the chest and abdominal regions and their phase relationships. Finally, based on a preset algorithm (e.g., chest amplitude significantly greater than abdominal amplitude indicates thoracic breathing, conversely, abdominal breathing, and similar and synchronized amplitudes indicate mixed breathing), the current breathing mode is distinguished. This system is particularly suitable for real-time control scenarios of respiratory exoskeletons: breathing pattern recognition results and deformation data can be output to the main controller of the respiratory exoskeleton in real time via a communication interface. The respiratory exoskeleton control system dynamically adjusts the output force, rhythm, and application site of the pneumatic unit or motor based on the received chest and abdominal deformation distribution and breathing pattern information. For example, when the breathing pattern is primarily thoracic, the exoskeleton can enhance the expansion of the thoracic region; in the case of abdominal breathing, it can increase the pressure or support on the abdomen, thereby achieving precise synchronization and personalized assistance between respiratory movements and exoskeleton-assisted actions.

[0076] Furthermore, this system can be seamlessly integrated with a respiratory exoskeleton. The sensing module is attached to the user's chest and abdomen surface to monitor the coupling relationship between pressure changes and chest and abdominal deformation in real time.

[0077] In addition, the system supports the cascading use of multiple modules to cover a wider area of ​​the chest and abdomen, enabling high-resolution monitoring and synergistic assistance of the entire respiratory muscle group.

[0078] It should be noted that in this embodiment, all functions, from analog front-end processing to digital signal processing and advanced algorithm recognition, can be implemented by an embedded system (such as an STM32 series main control chip), making the system not only powerful but also small in size and low in power consumption.

[0079] This system has undergone multi-dimensional optimization in terms of wearing comfort:

[0080] Material biocompatibility: Both the flexible circuit board and the optical dielectric layer are encapsulated with medical-grade silicone or polyurethane materials, which have good skin affinity, breathability and sweat corrosion resistance, and support long-term wear.

[0081] Lightweight design: The entire sensing module (including circuitry and optical layers) weighs less than 20g, making it comfortable to wear without feeling heavy.

[0082] Low power consumption operation: The system adopts an intermittent sampling and dynamic power management strategy, which can support more than 8 hours of continuous operation on a single charge, meeting the needs of daily rehabilitation training;

[0083] Cleaning and disinfection: The module surface supports wiping with medical alcohol or low-temperature plasma disinfection, and is reusable, suitable for multiple people or long-term rehabilitation scenarios.

[0084] In addition, the module supports wireless data transmission (such as Bluetooth Low Energy), which can wirelessly connect to the exoskeleton controller or host computer, further reducing cable constraints and improving the freedom of wearing and user experience.

[0085] like Figure 4 As shown, this embodiment also provides a method for using a wearable flexible optical waveguide array sensing system, including the following steps:

[0086] S10: Select a flexible optical waveguide array sensing module of appropriate size based on the user's chest and abdominal circumference and attach it to the surface of the chest and abdominal cavity.

[0087] Specifically, a flexible optical waveguide array sensing module of appropriate size is selected based on the user's abdominal and chest circumference parameters, so as to monitor the respiratory deformation of the user's chest and abdominal cavity surface using a flexible optical waveguide array sensing module of appropriate size.

[0088] S20: The signal acquisition and processing circuit acquires and processes the signal output by the flexible optical waveguide array sensing module, and then calculates the amplitude and phase difference of the light intensity change of each optical channel.

[0089] Specifically, the signal acquisition and processing circuit acquires and processes the signals output from each optical channel on the flexible optical waveguide array sensing module, and measures the light intensity changes of each optical channel, specifically measuring the amplitude and phase difference of the light intensity changes of each optical channel.

[0090] S30: Determine the breathing type based on amplitude and phase difference.

[0091] Specifically, the breathing type is determined based on the measured amplitude and phase difference, which includes thoracic breathing mode, abdominal breathing mode and mixed breathing mode.

[0092] It should be noted that, in determining the breathing type, temporal phase information is incorporated to overcome the limitation of traditional methods that rely solely on overall amplitude to distinguish breathing types. Specifically, after real-time acquisition of light intensity changes in each channel, the peak amplitude and time delay of each channel's signal are first calculated, and then the breathing mode is determined using an algorithm. The specific method is as follows:

[0093] When the amplitude of the upper array channel (near the sternum region) is significantly higher than that of the lower array (near the abdomen), and its peak phase appears earlier, the system determines it to be thoracic breathing.

[0094] When the lower array amplitude is dominant and the phase is leading, it is determined to be abdominal breathing;

[0095] When the amplitudes of the upper and lower channels are similar and the phases are synchronized, it is determined to be a mixed type of respiration.

[0096] S40: Based on the preset light intensity-deformation mapping model, the change in light intensity is converted into the surface deformation of the chest and abdomen in real time and displayed on the host computer in real time.

[0097] Simultaneously, deformation and breathing pattern data can be transmitted in real time to the respiratory exoskeleton control system for intelligent adjustment of the exoskeleton's drive units. For example, during rehabilitation training, if the system detects insufficient thoracic breathing, it can guide the exoskeleton to enhance chest expansion assistance; if abdominal breathing is weak, it adjusts the assistance strategy to activate diaphragmatic movement. Furthermore, the system can adaptively match the assistance level with breathing depth based on real-time changes in breathing intensity, avoiding over- or under-assistance, thereby improving the personalization, safety, and effectiveness of rehabilitation training.

[0098] Specifically, after the signal acquisition and processing circuit synchronously samples and processes the multi-channel signals, it converts the change in light intensity into the surface deformation of the chest and abdomen according to the preset light intensity-deformation mapping model, and converts the abstract light intensity voltage value into the surface deformation of the chest and abdomen with physical meaning, thereby realizing the quantification of the signal and displaying the data on the host computer in real time.

[0099] In this embodiment, the intensity-deformation mapping model incorporates an independent calibration mechanism for the array's local optical channels, with each pair of infrared light-emitting diode (LED) – photodiode (PD) units possessing independent calibration coefficients. The specific method is as follows:

[0100] In the flexible optical channel of this embodiment, infrared light emitted by infrared light-emitting diodes (LEDs) propagates within the encapsulation medium, and its propagation behavior is affected by the difference in refractive index of the materials and the geometry of the interfaces. Although the array is not a traditional long-distance fiber waveguide, the light still satisfies the basic principles of total internal reflection and interface reflection within the linear "optical path": the encapsulation medium is composed of a flexible transparent material with a high refractive index (n1), and the refractive index of the interface in contact with air or skin is lower (n2). When the incident angle θ1 satisfies Snell's law: When θ1 is greater than the critical angle θc = arcsin(n2 / n1), light undergoes local total internal reflection in the flexible medium, keeping most of the light transmitted within the medium. However, when the array is attached to the chest and abdomen during respiratory movements, the flexible interface undergoes micro-bending, stretching, or compression, altering the geometry of the local interface and leading to the following optical effects: 1. Changes in the local incident angle cause some light rays to no longer satisfy the total internal reflection condition, thus leaking into the external medium (increased scattering loss); 2. Bending loss occurs in the curved region, causing mode leakage of light rays in areas of high curvature.

[0101] In this embodiment, the change in light intensity is not directly calculated from the phase difference, but rather obtained through the change in the voltage signal output by the photodiodes in each channel. The phase difference is only used to distinguish the temporal relationship of deformation in different regions, while the change in light intensity reflects the amplitude of local deformation. The specific principle is as follows: when the flexible interface is deformed by force, the geometry of the optical channel changes, local light transmission loss increases, leading to a decrease in the light intensity received by the photodiode, and consequently a drop in the output voltage. The system calculates the rate of change of light intensity for each channel relative to the baseline to characterize the local surface deformation. Subsequently, the light signal is mapped into displacement data using the aforementioned "light intensity-deformation model."

[0102] Based on the above method, the flexible optical waveguide array sensing module 10 has a thickness of 4mm and can be attached to the surface of the user's chest and abdomen with medical adhesive film, specifically covering the respiratory muscle activity area from the upper sternum to the navel.

[0103] It should be noted that before using the system, the skin surface of the chest and abdomen (from the upper sternum to the area above the navel) should be cleaned and dried. The flexible optical waveguide array sensing module 10 should be aligned with and covered on a specific area of ​​the user's body surface through the medical adhesive film pre-placed or additionally applied on its back, that is, from the upper sternum down to the area above the navel. Apply slight pressure to make the module firmly adhere to the surface of the user's chest and abdomen through the medical adhesive film. Its 4mm thickness ensures that the module has good flexibility after attachment, can conform to the curve of the body surface, and achieve a close fit. Through the above operation, it is ensured that the module effectively covers the main respiratory muscle activity areas (such as the skin surface of the pectoralis major, intercostal muscles, rectus abdominis and other related muscle groups) in this area, preparing for subsequent sensing of deformation caused by these muscle activities.

[0104] The aforementioned flexible optical waveguide array sensing module 10 can be integrated into the wearable straps, chest armor, or abdominal belt structure of a respiratory exoskeleton, serving as its core physiological signal sensing unit. The module is lightweight and flexible, without affecting the overall wearing comfort and freedom of movement of the exoskeleton. In practical use, this module can form a closed-loop feedback with the exoskeleton control system: the sensing module collects chest and abdominal deformation signals in real time → the controller analyzes the breathing state and generates assistance commands → the exoskeleton actuator provides corresponding assistance → the sensing module monitors deformation changes again, realizing a dynamic adjustment closed loop of breathing-assistance-monitoring. This allows for continuous optimization of assistance strategies during long-term rehabilitation training, improving rehabilitation efficiency and the naturalness of human-machine collaboration.

[0105] Furthermore, this system can also be used for rehabilitation assessment and training guidance of respiratory exoskeletons. Through long-term monitoring and recording of patients' chest and abdominal movement patterns at different training stages, the system can generate quantitative indicators such as respiratory coordination, diaphragmatic activation level, and chest and abdominal movement ratio, helping doctors or therapists objectively assess rehabilitation progress and adjust the exoskeleton's training parameters accordingly. In addition, in home rehabilitation scenarios, the system can be combined with the exoskeleton's prompting functions (such as vibration and voice prompts) to guide patients to perform correct chest or abdominal breathing exercises, achieving self-rehabilitation without supervision.

[0106] This system features a respiratory coordination assessment function: by calculating the phase delay and amplitude ratio between signals from the chest and abdominal regions, it generates a "chest-abdominal coordination index" to quantify the degree of coordination in respiratory movements. During rehabilitation, this index dynamically reflects the improvement in the patient's breathing pattern, providing an objective assessment basis for rehabilitation progress.

[0107] The system can also integrate with a cloud-based rehabilitation platform, uploading training data to the cloud and using artificial intelligence algorithms to analyze the evolution of breathing patterns, providing data support for doctors to remotely adjust rehabilitation plans. Simultaneously, the system supports gamified guidance for breathing training, using real-time breathing feedback to control virtual scene interactions, improving patient compliance and engagement.

[0108] The accompanying drawings in this application are for illustrative purposes only. The dimensions and shapes of the components shown are not actual limitations but are merely schematic representations. In actual implementation, the components can be reasonably configured and adjusted according to specific needs and actual conditions.

[0109] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A wearable flexible optical waveguide array sensing system, characterized in that, Including a flexible optical waveguide array sensing module (10) attached to the surface of the user's chest and abdomen, and also including: The signal acquisition and processing circuit (20) is electrically connected to the signal and power supply interface (140) of the flexible optical waveguide array sensing module (10) and is used to acquire and process the signals output by the flexible optical waveguide array sensing module (10). The flexible waveguide array sensing module (10) includes two oppositely arranged flexible circuit boards (110) and a flexible optical medium layer (120) disposed between the two flexible circuit boards. Each flexible circuit board (110) is provided with a plurality of optical sensing units (130) arranged in an array. Each optical sensing unit (130) includes an emitter and a receiver symmetrically placed on a flexible circuit board (110) to form a pair of independent optical channels. The flexible optical waveguide array sensing module (10) senses the dynamic fluctuation of light intensity measured by the optical sensing unit (130) to detect the deformation of the chest and abdominal surface caused by breathing. The flexible optical medium layer (120) has a multi-layer structure, including: The first flexible dielectric layer (121) consists of two layers attached to the inner sides of the two flexible circuit boards (110); A second flexible dielectric layer (122) is disposed between two first flexible dielectric layers, and the refractive index of the second flexible dielectric layer is higher than that of the first flexible dielectric layer. The second flexible dielectric layer (122) and the first flexible dielectric layer (121) together constitute a flexible refractive surface. When the deformation of the chest and abdomen surface causes the flexible optical dielectric layer (120) to undergo micro-bending, stretching or compression deformation, the refraction path and transmission conditions of light in the flexible optical dielectric layer (120) change, thereby causing a change in the light intensity received by the receiving electrode. The emitting electrode is an infrared light-emitting diode, and the receiving electrode is a photodiode; The optical path between the infrared light-emitting diode and the corresponding photodiode is 4mm to 6mm; The signal acquisition and processing circuit acquires and processes the signal output by the flexible optical waveguide array sensing module, and then calculates the amplitude and phase difference of the light intensity change in each optical channel, and determines the breathing type based on the amplitude and phase difference. The breathing types include thoracic breathing, abdominal breathing, and mixed breathing.

2. The wearable flexible optical waveguide array sensing system according to claim 1, characterized in that, The spacing between any two adjacent optical sensing units (130) is 6 mm to 10 mm.

3. The wearable flexible optical waveguide array sensing system according to claim 2, characterized in that, The overall size of the flexible optical waveguide array sensing module (10) is 40mm x 40mm, and the optical sensing unit (130) integrates 9 to 16 units.

4. The wearable flexible optical waveguide array sensing system according to claim 3, characterized in that, The signal acquisition and processing circuit (20) includes: The main control chip (210) is used to synchronously sample and digitally filter signals from multiple optical channels, and convert the change in light intensity into the surface deformation of the chest and abdomen according to the preset light intensity-deformation mapping model. A transimpedance amplifier (220) is used to convert the photocurrent signal generated by the photodiode into a voltage signal and perform preliminary amplification. The signal conditioning module (230) is used to perform debiasing and secondary amplification on the amplified voltage signal; The filtering module (240) is used to filter out high-frequency noise in the signal; Analog-to-digital converter (250) is used to convert analog signals into digital signals.

5. A method of using the wearable flexible optical waveguide array sensing system according to any one of claims 1-4, characterized in that, Includes the following steps: Select a flexible optical waveguide array sensing module of appropriate size based on the user's chest and abdominal circumference and attach it to the surface of the chest and abdominal cavity. Based on the preset light intensity-deformation mapping model, the change in light intensity is converted into the surface deformation of the chest and abdomen in real time and displayed on the host computer in real time.

6. The method of use according to claim 5, characterized in that, The flexible optical waveguide array sensing module covers the area of ​​respiratory muscle activity from the upper sternum to the upper umbilicus.

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