In this paper, a flexible microstrip patch antenna sensor is proposed for monitoring of the moisture content of lubricating oil. The sensor identifies liquids having different effective dielectric constants by detecting changes in the resonance frequency. The proposed antenna comprises a radiation patch, a metal ground plane, and a PDMS substrate with microchannels. The microchannels are etched on the PDMS substrate. When the relative permittivity of the microfluidic channel is 1.8∼12.5, the operating frequency of the proposed antenna changes from 2.230 to 2.116 GHz, and the amplitude of the reflection coefficient is greater than −26.3 dB. The simulation and measurement results show that the proposed sensor can monitor the lubricating oil with different moisture contents, which can cause frequency separation of at least 20 MHz and achieve a good linear response. Therefore, the proposed sensor has the feasibility of monitoring the quality of lubricating oil.

中文翻译：

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微流控柔性基板集成微带天线传感器，用于感测润滑油中的水分

本文提出了一种柔性微带贴片天线传感器，用于监测润滑油中的水分含量。传感器通过检测共振频率的变化来识别具有不同有效介电常数的液体。所提出的天线包括辐射贴片，金属接地平面和具有微通道的PDMS基板。将微通道蚀刻在PDMS基板上。当微流体通道的相对介电常数为1.8〜12.5时，建议天线的工作频率从2.230变为2.116 GHz，反射系数的幅度大于-26.3 dB。仿真和测量结果表明，该传感器可以监测不同水分含量的润滑油，可能导致至少20 MHz的频率分离并获得良好的线性响应。因此，所提出的传感器具有监测润滑油质量的可行性。