A Wearable Capacitive Sensor Based on Ring/Disk-Shaped Electrode and Porous Dielectric for Noncontact Healthcare Monitoring

Ya-Nan Zheng; Zhe Yu; Guoyong Mao; Yunyao Li; Dhanapal Pravarthana; Waqas Asghar; Yiwei Liu; Shaoxing Qu; Jie Shang; Run-Wei Li

doi:10.1002/gch2.201900079

A Wearable Capacitive Sensor Based on Ring/Disk-Shaped Electrode and Porous Dielectric for Noncontact Healthcare Monitoring

Glob Chall. 2020 Mar 18;4(5):1900079. doi: 10.1002/gch2.201900079. eCollection 2020 May.

Authors

Ya-Nan Zheng^{1

2

3}, Zhe Yu^{1

2

3}, Guoyong Mao⁴, Yunyao Li^{1

3

5}, Dhanapal Pravarthana^{1

3}, Waqas Asghar^{1

3}, Yiwei Liu^{1

3}, Shaoxing Qu⁴, Jie Shang^{1

3}, Run-Wei Li^{1

3}

Affiliations

¹ CAS Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 P. R. China.
² College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Beijing 100049 P. R. China.
³ Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 P. R. China.
⁴ State Key Laboratory of Fluid Power and Mechatronic System Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Department of Engineering Mechanics Zhejiang University Hangzhou 310027 China.
⁵ College of Information Engineering Nanjing University of Finance and Economics Nanjing 210046 China.

Abstract

Wearable sensors are gradually enabling decentralized healthcare systems. However, these sensors need to be closely attached to skin, which is unsuitable for long-term dynamic health monitoring of the patients, such as infants or persons with burn injuries. Here, a wearable capacitive sensor based on the capacitively coupled effect for healthcare monitoring in noncontact mode is reported. It consists of a ring-shaped top electrode, a disk-shaped bottom electrode, and a porous dielectric layer with low permittivity. This unique design enhanced the capacitively coupled effect of the sensor, which enables a high noncontact detectivity of capacitance change. When an object approaches the sensor, its capacitance change (ΔC/C _i = -38.7%) is 3-5 times higher than that of previously reported sensors. Meanwhile, the sensor is insensitive to the stretching strain and pressure (ΔC/C _i < 5%) due to the unique ring-shaped electrode and the incompressible closed cells of the porous dielectric material, respectively. Finally, various human physiological signals (pulse and respiratory) are recorded in noncontact mode, where a person wears loose and soft clothes implanted with the sensor. Thus, it is promising to build smart healthcare clothes based on it to develop wearable decentralized healthcare systems.

Keywords: capacitively coupled effect; dielectric materials wearable sensors; noncontact healthcare monitoring.