面向可穿戴脉搏监测的柔性超材料谐振传感机理研究与性能调控

Wearable pulse sensors offer new opportunities for the prevention, control and clinical diagnosis of cardiovascular diseases because of their advantages of lightweight, high integration and noninvasive detection. However, current wearable sensing mechanisms are mainly based on sensing through electrical signals, which are vulnerable to signal hysteresis, electromagnetic interference and power consumption, thus difficult to accurately collect reliable pulse signals. This project focuses on sensing mechanism, sensing properties and fabrication methods, to meet the requirements of high sensitivity, high signal-to-noise ratio and high resolution fabrication for wearable pulse sensors. Emphases would be put on the following parts. Firstly, it studies the interaction mechanism between metamaterial resonator unit and its corresponding electromagnetic field, and reveals the relationship between dimensional changes caused by pulse beat and its equivalent inductance and capacitance, self-resonant frequency shift/magnitude, obtaining accurate controllable parameter range for pulse detection. Then it establishes a controllable model of metamaterial resonator unit types, geometrical change, array structure of different combination of metamaterial resonators, to sensing properties, realizing optimized metamaterial resonator structure with high sensitivity and improved signal-to-noise ratio. After that it explores highly efficient and controllable manufacturing processes to fabricate high resolution and stretchable array sensors. This project would realize a passive and wireless wearable pulse monitoring system to verify the sensing mechanism and properties, and some related results could provide a theoretical basis and technical support for the realization of wearable health monitoring devices.

可穿戴脉搏传感器以其轻薄便捷、集成度高和无创监测等特点，可为心血管系统类疾病的预防控制及临床诊断提供新机遇。然而，现有的可穿戴传感技术主要基于电信号感知，易受到信号回滞、电磁干扰及功耗等影响，存在对脉搏信号精确可靠采集的难题。本项目针对可穿戴脉搏传感系统的高灵敏度与高信噪比的要求，从传感机理、材料特性和制造方法等方面围绕“柔性超材料谐振传感与性能调控”科学问题展开多学科交叉研究。分析超材料谐振单元与电磁场交互作用机制，揭示脉搏微扰引起几何形变与响应频移/强度变化规律，获取脉搏精确检测可控参数区间；研究超材料谐振单元类型、结构参数、传感阵列拓扑结构对感知性能的调控机理，提出高灵敏度、高信噪比的超材料谐振单元优化方法；探索柔性超材料谐振阵列的高效可控制造工艺，制备高精度阵列化传感器件。项目通过构建无源无线可穿戴脉搏监测系统进行应用验证，相关成果为可穿戴健康监测器件的制造提供理论基础和技术源泉。

可穿戴传感技术具有电学性能优异、集成度高和能够连续监测等特点，为心血管疾病的预防提供了新机遇。脉搏传感技术以其便捷、无创等诸多优势，成为可穿戴人体健康监测领域最有前景的传感技术之一。本项目针对无源柔性超材料谐振传感机理在可穿戴脉搏监测领域的应用，开展理论、模拟和实验研究。通过多场调控实现超材料谐振结构参数、功能材料特性与电磁响应频移、强度损耗的可调控制，并探索柔性超材料谐振阵列化结构高效可控制造方法，同时结合提高无线信号读取距离的局域电磁场增强机制，实现具有高灵敏度、高信噪比和高准确性的无源无线可穿戴脉搏监测器件。首先，针对于超材料谐振传感机理的建模分析与实验验证。对双环结构的CSRR进行电磁场建模，并根据人体的手腕肌肉血液介电模型，分析在脉搏跳动情况下的电磁场微扰分布，并得出谐振环的等效电感电容与脉搏跳动之间的关系。其次，针对于柔性/可拉伸性材料性能及导电功能材料对超材料谐振单元性能的影响，先考虑不同谐振图案类型、阵列拓扑结构及其相互耦合作用、以及结构参数变化等对性能的影响，分析材料节电/损耗特性对响应的频移/强度影响规律，确定了所需的介电材料（PET薄膜及Rogers系列基板板材）以及导电材料（包括导电银浆、石墨烯导电材料等），并采用丝网印刷及光刻法来制备所设计的传感电路，再对制备出的阵列化传感器件进行疲劳拉伸测试以确定其稳定性与可靠性。为提高无线读取距离，设计了一频率自适应中继线圈，对贴附于不同个体手腕的传感器件进行脉搏测试并记录相应的结果。经数据采集与解调处理，得到所测试的脉搏信号，并通过测试的脉搏信号与人体正常脉搏信号比对，以评估被测人体状态。因此，通过设计制备的具有高信噪比和高准确度的无源无线可穿戴脉搏监测器件，获取待测者脉搏波的波形、频率、振幅等信息，来评估其血压及心率等参数，为可穿戴移动医疗健康监测器件的制造提供关键理论与技术支撑。