Stretchable Strain Sensor with Controllable Negative Resistance Sensitivity Coefficient Based on Patterned Carbon Nanotubes/Silicone Rubber Composites.

Rong Dong,Jianbing Xie

doi:10.3390/mi12060716

Abstract

In this paper, stretchable strain sensors with a controllable negative resistance sensitivity coefficient are firstly proposed. In order to realize the sensor with a negative resistance sensitivity coefficient, a stretchable stress sensor with sandwich structure is designed in this paper. Carbon nanotubes are added between two layers of silica gel. When the sensor is stretched, carbon nanotubes will be squeezed at the same time, so the sensor will show a resistance sensitivity coefficient that the resistance becomes smaller after stretching. First, nanomaterials are coated on soft elastomer, then a layer of silica gel is wrapped on the outside of the nanomaterials. In this way, similar to sandwich biscuits, a stretchable strain sensor with controllable negative resistance sensitivity coefficient has been obtained. Because the carbon nanotubes are wrapped between two layers of silica gel, when the silica gel is stretched, the carbon nanotubes will be squeezed longitudinally, which increases their density and resistance. Thus, a stretchable strain sensor with negative resistance sensitivity coefficient can be realized, and the resistivity can be controlled and adjusted from 12.7 Ω·m to 403.2 Ω·m. The sensor can be used for various tensile testing such as human motion monitoring, which can effectively expand the application range of conventional tensile strain sensor.

Highlights

Wearable technology tends to be more sophisticated than hand-held technology because it can provide skin-mountable biofeedback and tracking of physiological function
Stretchability and sensitivity are the key features of strain sensor which can be described by Strain (ε) and Gauge Factor (GF), respectively
The conductive particles such as nanoparticles (NPs) [3,4,5,6], carbon nanotubes (CNTs) [7,8,9,10], silver nanowires (AgNWs) [11,12], and graphene [13,14] are typically coated on soft elastomer, such as PDMS [13], Ecoflex [12,15], silicone elastomer [16,17], rubber [18,19], dragon-skin elastomer [20] et al In [15], super-stretchable, skin-mountable, and ultra-soft strain sensors are presented by using carbon nanotube percolation network-silicone rubber nanocomposite thin films, the stretchability can achieve 500%, but the GF is only 1–2.5

Summary

Introduction

Wearable technology tends to be more sophisticated than hand-held technology because it can provide skin-mountable biofeedback and tracking of physiological function. Paper sents a controllable resistance sensitivity coefficient stretchable strain presents a controllable resistance sensitivity coefficient stretchable strain sensor. The strain sensor presents a good optical transmittance, and gains the ability to monitor both the subtle motions of facial expressions and the large motions the ability to monitor bothbasis, the subtle motions facial expressionsstructure and the large motions of of human joints. On this we found thatofthe sandwich-like can obtain human joints. Of the sensor and its specific application will be developed in the following research

Principle and Design

Typical

Fabrication

Findings

Discussion

Resistivity of the stretchable strain sensors