Reconfigurable, Stretchable Strain Sensor with the Localized Controlling of Substrate Modulus by Two-Phase Liquid Metal Cells.

Linna Mao,Huanyu Cheng,Taisong Pan,Yizhen Ke,Jia Zhu,Yuan Lin,Junxiong Guo

doi:10.3390/nano12050882

Abstract

Strain modulation based on the heterogeneous design of soft substrates is an effective method to improve the sensitivity of stretchable resistive strain sensors. In this study, a novel design for reconfigurable strain modulation in the soft substrate with two-phase liquid cells is proposed. The modulatory strain distribution induced by the reversible phase transition of the liquid metal provides reconfigurable strain sensing capabilities with multiple combinations of operating range and sensitivity. The effectiveness of our strategy is validated by theoretical simulations and experiments on a hybrid carbonous film-based resistive strain sensor. The strain sensor can be gradually switched between a highly sensitive one and a wide-range one by selectively controlling the phases of liquid metal in the cell array with a external heating source. The relative change of sensitivity and operating range reaches a maximum of 59% and 44%, respectively. This reversible heterogeneous design shows great potential to facilitate the fabrication of strain sensors and might play a promising role in the future applications of stretchable strain sensors.

Highlights

Published: 7 March 2022Strain sensors, as a signal transducer, can convert external mechanical stimuli into electrical signals
A reconfigurable and stretchable strain sensor with multiple combinations of sensitivity and response range is realized by a novel heterogeneous substrate design
The introduction of the spiral cell array filled with two-phase liquid metal enables the local modulus modulation in the substrate and leads to strain redistribution in the active material

Summary

Introduction

As a signal transducer, can convert external mechanical stimuli into electrical signals. The stretchable strain sensor is a key part of wearable electronics that can be widely used in applications such as human health monitoring [1–3], artificial muscle [4,5], soft robot skin [6,7], and human–machine interfaces [8,9]. The high performance of such sensors largely relies on the strain transfer from the elastomer substrate to the conductive film, which leads to the crack propagation in active materials and change of conductive path [12,13]. To improve the sensitivity of strain sensors, many previous works have focused on the development of highly conductive materials, such as Ag nanowires [14], graphene [15–18], carbon nanotubes [19–21], and conductive composites [22–25]. The enhancement of sensitivity of the stretchable strain sensor is often accompanied with the degradation of response range

Methods

Results

Conclusion