基于LTCC的高温无源无线压力/温度集成传感器研究

The application of low temperature co-fired ceramic (LTCC) technique in LC resonant high temperature pressure sensors has drawn much attention in the wireless sensor research field. To solve the problems coming up in developing LTCC based passive wireless LC high temperature pressure sensor, such as serious temperature cross sensitivity, sensitivity constraint and unable to realize pressure/temperature simultaneous measurement, this project proposed to develop high performance pressure sensitive film using glass-ceramic based LTCC materials and use positive temperature coefficient (PTC) thick film as temperature sensitive LC resonant antenna electrode material. The pressure sensitive glass-ceramic with low Young’s modulus and high temperature stability of dielectric constant will be developed based on the effective medium theory of composites. PTC thick film will also be co-firable with the glass-ceramic LTCC material. The decoupling double LC resonant antennas are designed by the finite element analysis method. The integrated pressure and temperature LTCC sensor will be developed according to the simulated results. The pressure and temperature sensing features of the developed LTCC sensors under 600℃ would be clarified by analyzing the variations of impedance and resonant frequency. The achievements of this project will provide important principle and mechanism for developing multi-parameters integrated passive wireless LTCC sensor, which could work stably in high temperature harsh environment.

低温共烧陶瓷（LTCC）技术在电磁谐振式高温压力传感器中的应用研究引起了无线传感器研究领域的广泛关注。针对LTCC高温压力传感器研究中存在的温度交叉敏感、灵敏度受限以及压力/温度难以集成测量等问题，本项目从LTCC基板材料研究出发，提出采用微晶玻璃系LTCC材料作为压力敏感膜、PTC厚膜热敏材料作为LC谐振天线电极的研究思路。以复合材料的有效介质理论为基础，通过玻璃组分设计和烧结工艺优化，研究并获得低杨氏模量、高介电温度稳定的LTCC压力敏感膜材料，实现与PTC厚膜及银电极等异质材料的匹配共烧。设计了电感解耦的双LC谐振天线，结合有限元模拟计算，揭示其在压力和温度场下的电磁调谐规律，以此指导压力/温度集成的无源无线LTCC传感器的制备，并进行600℃高温下的压力和温度的敏感特性研究，为可在高温恶劣环境下稳定工作的多参数集成无源无线LTCC传感器的研制奠定坚实的理论和技术基础。

无源无线传感器不需要引线和电源供电便可进行信号的探测和传输，使用寿命长，维护简单，是未来传感器发展的重要方向。其中，基于电磁耦合原理的电感电容式（Inductor-Capacitor, LC）传感器由于工艺简单、载体灵活、价格低廉等优点，成为研究最广泛的无源无线传感器之一。低温共烧陶瓷（Low Temperature Co-fired Ceramics, LTCC）有着陶瓷和玻璃等无机材料固有的高熔点、高耐磨性和耐腐蚀等优点，是面向恶劣环境应用的传感器的理想载体。本项目研究获得了适合于传感器应用的LTCC基板材料，解决了LTCC基板材料与银电极共烧过程中的扩散问题，并揭示了银扩散机理。设计优化了LC射频天线结构，掌握了无牺牲层填充的LTCC空腔制备工艺，实现了LC射频天线和空腔结构的有效集成。系统研究了LTCC无源无线压力传感器在不同温度下的压力响应特性，发现了压力敏感膜厚度与检测限和灵敏度的关联关系，当压力敏感膜厚度为148 μm的传感器具有3.76 kHz/kPa的高灵敏度，具有432 μm压力敏感膜的传感器具有2660 kPa的高检测限。设计并制备了可同时感测压力和温度两个参数的双LC无源无线压力/温度集成传感器，在140-840 kPa，50-500 ℃范围内，压力/温度集成传感器对压力的灵敏度为1.16 kHz/kPa，随温度变化的灵敏度为0.062% dB/℃。本项目研究的相关成果为可在高温恶劣环境下稳定工作的多参数集成无源无线LTCC传感器研制奠定坚实的理论和技术基础。