Serpentine‐Inspired Strain Sensor with Predictable Cracks for Remote Bio‐Mechanical Signal Monitoring

Abstract

Flexible strain sensors have attracted intense interest due to their application as intelligent wearable electronic devices. However, it is still a huge challenge to achieve a flexible sensor with simultaneous high sensitivity, excellent durability, and a wide sensing region. In this work, a crack-based strain sensor with a paired-serpentine conductive network is fabricated onto flexible film by screen printing. The innovative conductive network exhibits a controlled crack morphology during stretching, which endows the prepared sensor with outstanding sensing characteristics, including high sensitivity (gauge factor up to 2391.5), wide detection (rang up to 132%), low strain detection limit, a fast response time (about 40 ms), as well as excellent durability (more than 2000 stretching/releasing cycles). Benefiting from these excellent performances, full-range human body motions including subtle physiological signals and large motions are accurately detected by the prepared sensor. Furthermore, wearable electronic equipment integrated with a wireless transmitter and the prepared strain sensor shows great potential for remote motion monitoring and intelligent mobile diagnosis for humans. This work provides an effective strategy for the fabrication of novel strain sensors with highly comprehensive performance.

Highly Stretchable, Highly Sensitive, and Antibacterial Electrospun Nanofiber Strain Sensors with Low Detection Limit and Stable CNT/MXene/CNT Sandwich Conductive Layers for Human Motion Detection

“…In addition, electrical stability of the CNT/MXene/CNT/TPU strain sensor is further characterized by the I – V curve under different stretching (Figure S6) and the Δ R / R 0 -strain curve at different stretching rates (Figure S7), which enable the sensor to accurately and timely transmit the signals captured in human motion detection to back-end processing equipment. Additionally, the performances of the CNT/MXene/CNT/TPU strain sensor and recent crack-based strain sensors are compared in terms of sensing range and sensitivity (Figure h), ,,− and the detailed parameters are shown in Table S1. It can be found that crack-based strain sensors are generally unable to combine a wide sensing range and high sensitivity.…”

Graphene/Carbon Nanotube Conductive Ink-Based Biomimetic Structure for Self-Powered Flexible Medical Monitoring Devices

“…Soft wearable sensing devices have attracted extensive research attention in the fields of e-skin, human health monitoring, and medical image-assisted diagnosis due to the advantages of integrated functions, high sensitivity response, and good biocompatibility. − However, the existing sensors are unable to achieve a highly sensitive response over a wide sensing range. , In addition, the sensors require external power supply during utilization. − These conditions hinder the further development of flexible wearable sensing devices. Soft wearable sensing devices having both highly sensitive response over a wide sensing range and self-powered sensing characteristics are the key issues requiring a solution at present.…”

Skin-Like Strain Sensors Based on Multiwalled Carbon Nanotube/Polydimethylsiloxane Composite Films

“…For example, flexible strain sensors based on MWCNTs/PDMS microspheres (MSs) showed a high strain range of more than 40% and high sensitivity (gauge factor, GF = 7.22); Ecoflex-based resistive-type sensors reinforced with CNTs showed a GF of 1–18 and a range of more than 200% with a linear response. − Although they have a wide response range, the sensitivity is low. Then, the structure design of the sensor has been extensively studied to improve the sensitivity, such as the snake-like conductive network, lotus leaf micro-pattern, scorpion bionic, and interlocking structure. , For example, graphene oxide/PDMS composite membranes with the nano-crack structure on the surface have a very high sensitivity under 0–1% tension (maximum GF is 8699). These crack-based sensors have high sensitivity due to crack breaking and closing under strain or vibration.…”

“…24−26 Although they have a wide response range, the sensitivity is low. Then, the structure design of the sensor has been extensively studied to improve the sensitivity, such as the snake-like conductive network, 27 lotus leaf micro-pattern, 28 scorpion bionic, 29 and interlocking structure. 30,31 For example, graphene oxide/PDMS composite membranes with the nanocrack structure on the surface 20 have a very high sensitivity under 0−1% tension (maximum GF is 8699).…”