Flexible Strain-Sensitive Silicone-CNT Sensor for Human Motion Detection

Natalia A Demidenko; Artem V Kuksin; Victoria V Molodykh; Evgeny S Pyankov; Levan P Ichkitidze; Victoria A Zaborova; Alexandr A Tsymbal; Svetlana A Tkachenko; Hassan Shafaei; Ekaterina Diachkova; Alexander Yu Gerasimenko

doi:10.3390/bioengineering9010036

Flexible Strain-Sensitive Silicone-CNT Sensor for Human Motion Detection

Bioengineering (Basel). 2022 Jan 13;9(1):36. doi: 10.3390/bioengineering9010036.

Authors

Affiliations

¹ Institute of Biomedical Systems, National Research University of Electronic Technology, 124498 Moscow, Russia.
² Institute of Bionic Technologies and Engineering, I.M. Sechenov First Moscow State Medical University, 119991 Moscow, Russia.
³ Institute of Clinical Medicine, I.M. Sechenov First Moscow State Medical University, 119991 Moscow, Russia.
⁴ Sports Adaptology Laboratory, Moscow Institute of Physics and Technology, 141701 Dolgoprudny, Russia.
⁵ Department of Pathophysiology, I.M. Sechenov First Moscow State Medical University, 119991 Moscow, Russia.
⁶ Department of Physical Rehabilitation Massage and Health-Improving Physical Culture, Russian State University of Physical Education, Sport, Youth and Tourism (SCOLIPE), 105122 Moscow, Russia.
⁷ Department of Oral Surgery, Borovskiy Institute of Dentistry, I.M. Sechenov First Moscow State Medical University, 119991 Moscow, Russia.

Abstract

This article describes the manufacturing technology of biocompatible flexible strain-sensitive sensor based on Ecoflex silicone and multi-walled carbon nanotubes (MWCNT). The sensor demonstrates resistive behavior. Structural, electrical, and mechanical characteristics are compared. It is shown that laser radiation significantly reduces the resistance of the material. Through laser radiation, electrically conductive networks of MWCNT are formed in a silicone matrix. The developed sensor demonstrates highly sensitive characteristics: gauge factor at 100% elongation -4.9, gauge factor at 90° bending -0.9%/deg, stretchability up to 725%, tensile strength 0.7 MPa, modulus of elasticity at 100% 46 kPa, and the temperature coefficient of resistance in the range of 30-40 °C is -2 × 10^-3. There is a linear sensor response (with 1 ms response time) with a low hysteresis of ≤3%. An electronic unit for reading and processing sensor signals based on the ATXMEGA8E5-AU microcontroller has been developed. The unit was set to operate the sensor in the range of electrical resistance 5-150 kOhm. The Bluetooth module made it possible to transfer the received data to a personal computer. Currently, in the field of wearable technologies and health monitoring, a vital need is the development of flexible sensors attached to the human body to track various indicators. By integrating the sensor with the joints of the human hand, effective movement sensing has been demonstrated.

Keywords: CNT networks; carbon nanotubes; flexible bioelectronics; health monitoring; laser radiation; nanocomposites; strain sensors; wearable electronics.