Highly Inductive Coil Spring Strain/Compress Sensors Integrated with Shape Memory Alloy and Shape Memory Polymers-CNTs

Future wearable electronic gadgets offer great potential for using stretchable, strain-sensitive materials to instantly detect human motion and record physiological information. This paper presens a strain/compress sensor made from a Shape memory alloy (SMA) coil spring covered with silver pastes and the composite of carbon nanotubes and Shape memory polymer (SMP). The combination of the shape memory materials that expand or contract automatically by temperature improved the mechanics of the sensor. First, the proposed sensors showed an excellent ability to broad-range strain of 250% and compress of 50% with a relative inductance ( increment L/L0) range from -35% to 50%, respectively. Durability during 1000 loading and unloading cycles at 200% strain is included. Secondly, by monitoring changes in resistance, inductance, and time, it is determined how many silver layers appropriate for transformation should be in order to improve the recovery time of the SMA coil spring. Moreover, the presence of CNTs in the composite-covered outer of sensors helps to reduce the influence of the relation between resistance and temperature in the range from 30 & DEG;C to 110 & DEG;C. Finally, a device is suggested for monitoring arm and triceps brachii muscle movements based on the stretchable area as a key parameter. The combination of the shape memory materials that expand or contract automatically by temperature improved the mechanics of the sensor. The study presented a novel approach to fabricating a highly retractable and stretchable inductive sensor based on an SMA coil spring covered with silver and CNTs/SMP layers, aiming to create a wearable arm sleeve to detect arm workouts.image

Automated summary

This study presents a highly stretchable strain/compress sensor based on a shape memory alloy coil spring covered with silver and CNTs/SMP layers. The combination of shape memory materials improves the sensor's mechanics, and the presence of CNTs helps reduce the influence of temperature on resistance. The proposed device can be used to monitor arm and triceps brachii muscle movements, providing a novel approach for wearable arm sleeves.