Three-Dimensional Interfacial Stress Sensor Based on Graphene Foam

The measurement of pressure is one of the most important functions of the artificial skin. In general, most of the pressure is not only coupled with the vertical normal interfacial stress (Z-direction) but also the parallel shear interfacial stress (X- and Y-direction). It is very important to develop a sensor to measure the 3-D interfacial stress. This paper presents a 3-D interfacial stress sensor based on graphene foams and super-elastic materials. A data-fitted measurement model is constructed to calculate the 3-D interfacial stress. The sensor is measured by utilizing a resistive measurement circuit, and experiments are performed with a 3-D stress simulation system. Results show that the fabricated sensor is capable of measuring the normal stress at a range of 0-50 kPa with a sensitivity of 0.0270 kPa(-1) and the shear stress at a range of 0-25 kPa with a sensitivity of 0.0169 kPa(-1). The response time of the sensor is 80 ms, which is less than the human response time. By taking advantage of the graphene foam, our sensor has a high sensitivity, good stability, and has potential application in the fields of artificial skin, intelligent robot, wearable electronics, and prosthetics.