Sezen A S, Sivaramakrishnan S, Hur S, Rajamani R, Robbins W, Nelson B J
University of Minnesota, 1100 Mechanical Engineering, 111 Church Street SE, Minneapolis, MN 55455, USA.
J Biomech Eng. 2005 Nov;127(6):1030-4. doi: 10.1115/1.2049330.
This paper introduces passive wireless telemetry based operation for high frequency acoustic sensors. The focus is on the development, fabrication, and evaluation of wireless, battery-less SAW-IDT MEMS microphones for biomedical applications. Due to the absence of batteries, the developed sensors are small and as a result of the batch manufacturing strategy are inexpensive which enables their utilization as disposable sensors. A pulse modulated surface acoustic wave interdigital transducer (SAW-IDT) based sensing strategy has been formulated. The sensing strategy relies on detecting the ac component of the acoustic pressure signal only and does not require calibration. The proposed sensing strategy has been successfully implemented on an in-house fabricated SAW-IDT sensor and a variable capacitor which mimics the impedance change of a capacitive microphone. Wireless telemetry distances of up to 5 centimeters have been achieved. A silicon MEMS microphone which will be used with the SAW-IDT device is being microfabricated and tested. The complete passive wireless sensor package will include the MEMS microphone wire-bonded on the SAW substrate and interrogated through an on-board antenna. This work on acoustic sensors breaks new ground by introducing high frequency (i.e., audio frequencies) sensor measurement utilizing SAW-IDT sensors. The developed sensors can be used for wireless monitoring of body sounds in a number of different applications, including monitoring breathing sounds in apnea patients, monitoring chest sounds after cardiac surgery, and for feedback sensing in compression (HFCC) vests used for respiratory ventilation. Another promising application is monitoring chest sounds in neonatal care units where the miniature sensors will minimize discomfort for the newborns.
本文介绍了基于无源无线遥测的高频声学传感器操作。重点在于用于生物医学应用的无线、无电池声表面波叉指换能器（SAW-IDT）微机电系统（MEMS）麦克风的开发、制造和评估。由于无需电池，所开发的传感器体积小，且采用批量制造策略成本低廉，这使其能够用作一次性传感器。已制定了一种基于脉冲调制表面声波叉指换能器（SAW-IDT）的传感策略。该传感策略仅依赖于检测声压信号的交流分量，无需校准。所提出的传感策略已在内部制造的SAW-IDT传感器和模拟电容式麦克风阻抗变化的可变电容器上成功实现。已实现高达5厘米的无线遥测距离。一种将与SAW-IDT器件配合使用的硅MEMS麦克风正在进行微加工和测试。完整的无源无线传感器组件将包括通过引线键合连接在SAW基板上并通过板载天线进行询问的MEMS麦克风。这项关于声学传感器的工作通过引入利用SAW-IDT传感器的高频（即音频频率）传感器测量开辟了新领域。所开发的传感器可用于多种不同应用中的身体声音无线监测，包括监测呼吸暂停患者的呼吸声、心脏手术后的胸部声音，以及用于呼吸通气的压缩（HFCC）背心的反馈传感。另一个有前景的应用是在新生儿重症监护病房监测胸部声音，其中微型传感器将使新生儿的不适感降至最低。
