Flexible tactile sensor based on reduced graphene oxide and polydimethylsiloxane

Abstract

Fabrication of flexible tactile sensor has been extensively investigated for various applications in robotic, biomedical and automotive fields. Although many research works have been proposing various kinds of tactile sensor design, there is still room for improvement, especially on the simplicity of the structure and understanding of the device operation. In this work, simple tactile sensor was fabricated using reduced graphene oxide (rGO) and polydimethylsiloxane (PDMS). The proposed sensor is made from two PDMS layers which were attached with rGO film and copper electrodes. The rGO film on PDMS layer was fabricated via drop-casting of graphene oxide dispersion and reduction using ascorbic acid. The copper electrode on PDMS was fabricated through photolithography and wet etching. Tactile sensors with reduced graphene oxide film deposited using dispersion concentration varied from 0.4 to 1 mg/ml were fabricated and analyzed. The fabricated sensors were characterized under application of force between 0.5 to 1.4 N. The fabricated device successfully worked as tactile sensor, whereas the resistance decreased as the applied force increased. This is due to the increase of contact area between reduced graphene oxide and electrode. Real time response test confirmed the device functionality. It was found that the sensor made from 0.8 mg/ml gave the highest sensitivity at 10.3 MΩ/N. Compared to other reported works, the proposed flexible sensor structure is relatively simple and can be fabricated using less complicated process. Thus, it is favorable for mass production of the low-cost tactile sensor.