非侵入式无线无源MEMS眼压传感器研究

Continuous monitoring of the intraocular pressure (IOP) is upmost important for glaucoma diagnosis and treatment, which cannot be realized by conventional IOP sensors due to their bulky designs. With the development of MEMS (Micro-Electro-Mechanical Systems) technologies, miniaturized IOP sensors have demonstrated the possibilities of continuous monitoring of IOP. However, the reported micro-machined IOP sensors suffer from the problems of the requirement of implantation or complicated structures with limited resolutions, rendering their use in glaucoma diagnosis ineffective. To address these issues, in this study, a non-invasive high-sensitivity IOP micro sensor based on a simple structure design of an LC tank is proposed. Since mutual inductance is the detection mechanism used in this sensor, this IOP sensor is wireless and power free, further simplifying the device design. Key research components of this study include 1) modeling of the relationship between IOP and the sensor detecting unit with the purpose of resolution enhancement; 2) theoretical analysis and calculation of the IOP sensor performance based on the LC tank and the mutual inductance detection mechanism; 3) development of microfabrication procedures compatible with flexible substrates ensuring device biocompatibility; 4) development of environmental adaptability for the IOP micro sensor; 5) development of information acquisition algorithms and peripheral detection circuits for the wireless and power-free IOP sensor and 6) calibration and validation of the IOP sensor based on animal testing. The proposed continuous IOP monitoring sensor has the advantages of non-invasiveness without the requirement of implantation, simple device structure without the requirement of extra integrated circuits for signal processing as well as high sensitivity and low cost. In the long term, this detection methodology may push forward the development of the ophthalmology research as well as the diagnosis and treatment of glaucoma.

准确、连续监测眼压对青光眼诊断和治疗具有非常重要的意义。临床用常规眼压计仅能测量单次眼压，MEMS技术使眼压连续监测成为可能。已报道的眼压微传感器或需手术植入，或结构复杂，灵敏度低，尚不能满足临床需求。本项目提出一种基于LC振荡回路和互感检测原理的新型非侵入式无线无源眼压微传感器，重点研究：眼压与传感器敏感单元的力学耦合模型和增敏机理；基于LC振荡回路和互感检测的眼压传感器理论分析与设计计算；基于生物兼容性的柔性衬底敏感单元的MEMS加工方法和眼压传感器环境适应性；眼压传感器无线无源信息获取方法和眼压信号提取算法；眼外控制器检测电路和便携式眼压测量仪；非侵入式无线无源眼压传感器动物试验等。 本项目所研究的非侵入式无线无源眼压微传感器结构简单，无需额外集成信号处理和电源模块，可实现眼压连续监测，具有灵敏度高、制造简单、成本低等优点，为眼科学基础研究和青光眼的诊断治疗提供新的检测方法和技术手段

眼压的长期、连续监测对青光眼的诊断和治疗具有非常重要的意义，目前临床常用的眼压计操作复杂并且仅能实现单次眼压测量。随着科技的发展以及MEMS技术在传感器领域的广泛应用，MEMS眼压传感器使得连续监测眼压成为可能。但是现有的MEMS眼压传感器存在着灵敏度低、中心谐振频率高、结构复杂、加工工艺难度大等问题，尚不能满足实际应用的需求。.为了解决上述问题，本项目研究了一种非侵入式无线无源MEMS眼压传感器。该传感器为五层堆叠式结构，采用Parylene做为传感器的衬底层，铜做为电极层，PDMS做为介电层，其中电极层和介电层构成两个电感和两个电容，形成串联谐振电路，该电路的信号被外部检测设备以无线无源的方式获取，从而得到眼压信息。取得的主要研究成果包括：（1）通过理论分析和仿真计算研究了眼压与传感器敏感单元的力学耦合模型和增敏机理，得到了传感器的直径、厚度、结构等最优参数；（2）提出了一种C-L-C-L串联回路的传感器结构，这种结构采用两个电容分别作为敏感电容和连接电容，能够解决现有传感器的引线键合问题，降低制作难度、提高可靠性；（3）采用MEMS 平面工艺和热塑形方法制作出了能够与眼球紧密贴合的曲面眼压传感器，增大了眼压信号的强度和灵敏度，优化了柔性材料的制备工艺以及电镀、刻蚀等关键的MEMS工艺和曲面塑形操作方法；（4）基于射频-监听原理研制了便携式眼压传感器的信号采集系统，采用FPGA开发板、AD/DA电路、蓝牙模块、上位机软件等搭建了眼压传感器的性能测试平台和实时监控系统；（5）本项目研究的非侵入式无线无源MEMS眼压传感器具有结构简单、成本低等优点，能够长期、连续监测眼压。实验测试结果表明：该眼压传感器的中心谐振频率降低到了40MHz，相对灵敏度达到1028.57ppm/kPa，能够分辨出最小50Pa（0.375mmHg）的眼压值变化，在青光眼的诊断治疗等领域具有一定的应用前景；（6）完成期刊和会议论文16篇，申请国家发明专利4项(2项已授权）；培养4名硕士研究生和2名博士研究生。