DTA - Graphene Based Transparent Strain Sensors

Transparent strain sensors have applications in: in situ monitoring of structures, highly compliant sensing films (e-skin), body mounted electronics for health monitoring, and soft robotics. Graphene offers a potential solution to this problem by providing a method to manufacture large area transparent conducting films. Piezoresistive sensors have been fabricated from these films, but the mechanism that relates film electrical resistance and mechanical strain (the gauge factor) is not fully understood.

This project will study single atom layer thickness flakes of reduced graphene oxide (rGO) deposited on polymer films. Strain sensing is achieved by introducing a controlled pattern of cracks within the film. These will be characterized using optical and electron microscopy, Raman spectroscopy and electrical measurements including electrical impedance spectrography and cyclic voltammetry. We wish to understand the mechanisms that lead to the initial crack network required to introduce the strain sensing ability of the films and how this network controls the observed piezoresistive effect. Existing models are empirical or phenomenological; this project will develop new models based on stochastic resistor networks to introduce physical rigor to the interpretation. This will be carried out over a range of temperature, humidity and similar, ranges to represent the working ranges in different applications. Our previous work has shown that these network models can also be used to interpret the damage that occurs to similar networks of nanowires and we will seek to incorporate the principles of the simpler 1D material model to assemblies of 2D materials. Practical strain sensors optimized for either high sensitivity and low maximum strain operability or lower sensitivity but high maximum strain will be developed and trialed for a range of applications. For example, we have an existing project placing strain sensors on the in-vitro models of outer wall of the bowel for monitoring bowel movement, with this application co-designed with users. It gives a potentially short route to impact.  

The student will be based in the Henry Royce Institute and work closely with both the Nano and Functional Materials Group and the Bioelectronics Group. Experiments will also be carried out using facilities in the National Graphene Institute and the Graphene Engineering Innovation Centre. This provides a highly interdisciplinary environment ideal for the projects aim to explore the fundamental principles of a device architecture and to develop it for real world applications.