Laser-Formed Sensors with Electrically Conductive MWCNT Networks for Gesture Recognition Applications

Abstract

Currently, an urgent need in the field of wearable electronics is the development of flexible sensors that can be attached to the human body to monitor various physiological indicators and movements. In this work, we propose a method for forming an electrically conductive network of multi-walled carbon nanotubes (MWCNT) in a matrix of silicone elastomer to make stretchable sensors sensitive to mechanical strain. The electrical conductivity and sensitivity characteristics of the sensor were improved by using laser exposure, through the effect of forming strong carbon nanotube (CNT) networks. The initial electrical resistance of the sensors obtained using laser technology was ~3 kOhm (in the absence of deformation) at a low concentration of nanotubes of 3 wt% in composition. For comparison, in a similar manufacturing process, but without laser exposure, the active material had significantly higher values of electrical resistance, which was ~19 kOhm in this case. The laser-fabricated sensors have a high tensile sensitivity (gauge factor ~10), linearity of >0.97, a low hysteresis of 2.4%, tensile strength of 963 kPa, and a fast strain response of 1 ms. The low Young’s modulus values of ~47 kPa and the high electrical and sensitivity characteristics of the sensors made it possible to fabricate a smart gesture recognition sensor system based on them, with a recognition accuracy of ~94%. Data reading and visualization were performed using the developed electronic unit based on the ATXMEGA8E5-AU microcontroller and software. The obtained results open great prospects for the application of flexible CNT sensors in intelligent wearable devices (IWDs) for medical and industrial applications.

Highly sensitive strain sensors based on dispensing technology for human–machine interaction

“…For example, Zhuo et al [26] successfully prepared a novel hybrid e-fiber sensor based on polydimethylsiloxane (PDMS)/multi walled carbon nanotubes (MWCNTs) with an optimal M/P ratio of 6 wt% and adopted textile technology as a new packaging method for this soft electronic sensor to create wearable, but its sensitivity as a tensile sensor is only 1.4405. Nikitina et al [27] proposed a method for forming an MWCNT conductive network in an organic silicone elastomer matrix to make stretchable sensors sensitive to mechanical strain. Although an assembled intelligent system based on a laser formed sensor with a conductive MWCNT network has achieved 94% accuracy in gesture recognition, the sensitivity of the sensor is low (average GF = 10).…”

Editorial for the Special Issue on Flexible and Wearable Sensors

“…In this Special Issue on Flexible and Wearable Sensors, we have included 25 papers, including 24 research papers, covering applications in human-computer interaction [ 1 , 2 , 3 ], mechanical design [ 4 , 5 , 6 , 7 , 8 ], health monitoring [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ], manufacturing technology [ 16 , 17 , 18 , 19 , 20 ], algorithms [ 21 , 22 , 23 ], and smart cities [ 24 ]. Additionally, we feature an intriguing review paper focusing on flexible wearable sensor devices for biomedical applications [ 25 ].…”