A graphene rheostat for highly durable and stretchable strain sensor

Abstract

Strain sensors for human health monitoring are of paramount importance in wearable medical diagnostics and personal health monitoring. Despite extensive studies, strain sensors with both high durability and stretchability are still desired, particularly with the stability for different environmental conditions. Here, we report a series of strain sensors possessing the graphene network with a high density of intermittent physical interconnections, which produces the relative resistance change by varying the overlap area between the neighboring graphene sheets under stretching and releasing, analogous to the slide rheostat working in electronics. Our in‐situ transmission electron microscope observation reveals the full recoverability of the structure from large deformation upon unloading for ensuring the exceptional cycle stability of our material on monitoring full‐range body movements. The stable response is also demonstrated over wide temperature range and frequency range, because the peculiar dynamic structure can be maintained through the self‐adjustment to the thermal expansion of the bulk material. Based on the working mechanism of graphene “slide rheostat,” the sensing properties of the strain sensor are tailored by tuning the graphene network structure with different mass densities using different concentrations of graphene oxide dispersion, while the stretchability and sensitivity can be separately optimized for different application requirements.

In Situ Dynamic Manipulation of Graphene Strain Sensor with Drastically Sensing Performance Enhancement

“…The separation stage can be observed and analyzed by transmission electron microscopy (TEM). [ 18,19 ]…”

Static Characteristics of a Linear Bipotentiometer Sensor

“…In order to improve the application performance of the existing linear potentiometer sensor, many methods are proposed [13][14][15], and some of them are effective. In this paper, based on an existing linear potentiometer sensor, a new scheme of a linear bipotentiometer sensor is proposed, the sensitive part of which is composed of two identical linear potentiometers.…”

Strain engineering of two‐dimensional materials: Methods, properties, and applications

“…Reproduced with permission: Copyright 2010, Elsevier B.V. (D) Schematic of the overlapped graphene sheets before and after applying tensile strain. Demonstration of graphene strain sensors for monitoring (E) the breathing and (F) the speaking tasks 134 . Reproduced with permission: Copyright 2019, The Authors.…”

“…As shown in Figure 7(C), when graphene film is subjected to compressive strain or tensile strain, the overlapping areas between adjacent graphene sheets become smaller or larger, which increases or decreases the resistance, respectively 133 . Based on this mechanism, Xu et al used partially overlapped graphene sheets in the slide rheostat for stretchable strain sensors, and the piezoresistive sensitivity of these sensors was much higher than that of stacked graphene strain sensors 134 . In Figure 7(D), the adjacent graphene sheets slipped relatively to each other under tensile strain, resulting in the decrease of contact area and the increase of resistance.…”