A laser scribed graphene oxide and polyimide hybrid strain sensor

Abstract

Strain sensors are devices used in applications such as electronic skin, prosthetic limbs, e-textiles, and many more, for measuring the physical elongation of a desired structure under a given or applied force. An artificial throat, using a strain sensor, was recently developed as an aid for speech impaired individuals. Strain sensors have been developed using graphene and polydimethylsiloxane (PDMS), with a reported gauge factor ranging from 5∼120. In this work, a strain sensor was developed through laser scribing. Laser scribing is a recent and facile technology used for printed electronics, whereby complex geometries and patterns can be drawn very easily. The laser scribing method relies on the property of certain materials to form a graphene-like conductive material upon irradiation by lasers. Polyimide and graphene oxide (GO) are two such materials. In these experiments, 2×3 cm sheets of polyimide were taken and a 1×1 cm box on the sheet was printed using a laser patterning setup of 450 nm wavelength. Graphene oxide solution was drop-casted on the reduced polyimide sheet of 1×1 cm, to increase its sensitivity, and then the drop-casted graphene oxide is reduced using the same laser. The strain sensor was characterized by a micro-strain testing machine. In the preliminary results, the normalized resistance was plotted against strain and the gauge factor (GF) was calculated. The intensity of the laser was varied, and different gauge factors were calculated. The effect of laser intensity was investigated. The gauge factor was found to be in the range of 49-54 and was compared with the polyimide reduced strain sensor (without drop-casting process).