3 years ago

Wearable Microfluidic Diaphragm Pressure Sensor for Health and Tactile Touch Monitoring

Wearable Microfluidic Diaphragm Pressure Sensor for Health and Tactile Touch Monitoring
Hossain M. Fahad, Wei Gao, Ethan W. Schaler, Kevin Chen, Li-Chia Tai, Ali Javey, Anzong Zheng, Hiroki Ota, Yuji Gao, Peida Zhao, Furui Xiong, Ronald S. Fearing, Yonggang Leng, Chuchu Zhang, Allan Zhao
Flexible pressure sensors have many potential applications in wearable electronics, robotics, health monitoring, and more. In particular, liquid-metal-based sensors are especially promising as they can undergo strains of over 200% without failure. However, current liquid-metal-based strain sensors are incapable of resolving small pressure changes in the few kPa range, making them unsuitable for applications such as heart-rate monitoring, which require a much lower pressure detection resolution. In this paper, a microfluidic tactile diaphragm pressure sensor based on embedded Galinstan microchannels (70 µm width × 70 µm height) capable of resolving sub-50 Pa changes in pressure with sub-100 Pa detection limits and a response time of 90 ms is demonstrated. An embedded equivalent Wheatstone bridge circuit makes the most of tangential and radial strain fields, leading to high sensitivities of a 0.0835 kPa−1 change in output voltage. The Wheatstone bridge also provides temperature self-compensation, allowing for operation in the range of 20–50 °C. As examples of potential applications, a polydimethylsiloxane (PDMS) wristband with an embedded microfluidic diaphragm pressure sensor capable of real-time pulse monitoring and a PDMS glove with multiple embedded sensors to provide comprehensive tactile feedback of a human hand when touching or holding objects are demonstrated. Herein, a flexible microfluidic diaphragm pressure sensor using liquid-metal microchannels is presented. The sensor is capable of detecting sub-100 Pa pressures with sub-50 Pa resolution. As a proof of concept, both heart-rate monitoring and tactile pressure mapping of a glove with multiple embedded sensors are demonstrated.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adma.201701985

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