Liquid metal electrode-enabled flexible microdroplet sensor

作者：Renchang Zhang, Zi Ye, Meng Gao, Chang Gao, Xudong Zhang, Lei Li, Lin Gui · 发表于：Lab on a Chip · 年份：2019 · DOI：10.1039/c9lc00995g · 被引用次数：27 · 研究领域：Innovative Microfluidic and Catalytic Techniques Innovation、Electrowetting and Microfluidic Technologies、Nanomaterials and Printing Technologies

This study presented a flexible liquid metal-based microdroplet capacitive sensor that would simply and accurately measure the speed and length of droplets flowing in microchannels. A pair of coplanar U-shaped electrodes was used to form a capacitance through droplet microchannels. Liquid metal was injected into polydimethylsiloxane (PDMS) channels to form the U-shaped electrodes. The sensor would generate a multi-plateau capacitance waveform as a droplet passes through the sensing area, and each plateau period corresponds to the droplet position in the sensing area. The droplet speed and length would be directly calculated from the multi-plateau capacitance waveform. The errors for the capacitive result relative to the real value were <7.2% for length and <2.8% for speed. Moreover, the sensor still maintained excellent performance for droplet length and speed measurement even though the microfluidic chip was bent to 96°. We have demonstrated that the capacitive sensor would be used for sweat rate monitoring.