Wearable Microfluidic Diaphragm Pressure Sensor for Health and Tactile Touch Monitoring |
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Authors: | Yuji Gao Hiroki Ota Ethan W Schaler Kevin Chen Allan Zhao Wei Gao Hossain M Fahad Yonggang Leng Anzong Zheng Furui Xiong Chuchu Zhang Li‐Chia Tai Peida Zhao Ronald S Fearing Ali Javey |
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Affiliation: | 1. Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA, USA;2. Berkeley Sensor and Actuator Center, University of California, Berkeley, CA, USA;3. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA;4. School of Mechanical Engineering, Tianjin University, Tianjin, China;5. Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin, China;6. National Center for Computer Animation, Bournemouth University, Bournemouth, UK |
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Abstract: | 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. |
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Keywords: | diaphragm pressure sensors flexible pressure sensors liquid metal microfluidics wearable |
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