Electrical and Computer Engineering Department, McGill University, Montreal, QC H3A 0E9, Canada.
MEMS Vision International Inc., Montreal, QC H4P 2R9, Canada.
Sensors (Basel). 2022 Jul 9;22(14):5157. doi: 10.3390/s22145157.
This paper proposes a novel integrated micro-viscometer for engine-oil monitoring. The final solution consists of a capacitive micromachined ultrasonic transducer (CMUT) and an application-specific integrated circuit (ASIC). The CMUT is used to generate and capture acoustic waves while immersed in engine oil. The low power transceiver ASIC is interfaced with the CMUT structure for actuation and reception. An integrated charge pump boosts the supply voltage from 3.3 to 22 V to generate the DC polarization voltage of the CMUT. The receiver has a power consumption of 72 µW with an input-referred noise current of 3.2pAHz and a bandwidth of 7 MHz. The CMUT array occupies an area of 3.5 × 1 mm, whereas the ASIC has a chip area of 1 × 1 mm. The system was tested using engine oils of different types and ages at different temperatures. Measurement results show a significant frequency shift due to the dynamic viscosity change that occurs as oil ages. A shift of -1.9 kHz/cP was measured, which corresponds to a shift of 33 Hz/mile. This work paves the way for high accuracy-integrated solutions for oil condition monitoring and is expected to play a significant role in a more economic and environmentally friendly usage of oil.
本文提出了一种新颖的集成微粘度计，用于发动机油监测。最终的解决方案由电容式微机械超声换能器 (CMUT) 和专用集成电路 (ASIC) 组成。CMUT 用于在机油中产生和捕获声波。低功耗收发器 ASIC 与 CMUT 结构接口，用于驱动和接收。集成电荷泵将电源电压从 3.3V 提升至 22V，以产生 CMUT 的直流偏置电压。接收器的功耗为 72µW，输入参考噪声电流为 3.2pAHz，带宽为 7MHz。CMUT 阵列的面积为 3.5×1mm，而 ASIC 的芯片面积为 1×1mm。该系统在不同温度下使用不同类型和老化程度的发动机油进行了测试。测量结果表明，由于油老化导致动态粘度变化，出现了显著的频率偏移。测量到-1.9kHz/cP 的偏移，相当于 33Hz/英里的偏移。这项工作为高精度集成的油况监测解决方案铺平了道路，有望在更经济和环保的油的使用方面发挥重要作用。
