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.

中文翻译：

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启用液态金属电极的柔性微滴传感器。

这项研究提出了一种基于液态金属的柔性微滴电容式传感器，该传感器将简单，准确地测量微通道中液滴的速度和长度。一对共面的U形电极用于通过微滴微通道形成电容。将液态金属注入聚二甲基硅氧烷（PDMS）通道中，以形成U形电极。当液滴穿过感测区域时，传感器将产生多平台电容波形，并且每个平稳周期对应于液滴在感测区域中的位置。液滴的速度和长度将直接从多平台电容波形中计算得出。电容结果相对于实际值的误差，长度<7.2％，速度<2.8％。而且，即使微流体芯片弯曲到96°，该传感器在液滴长度和速度测量方面仍保持出色的性能。我们已经证明，电容式传感器将用于出汗率监测。