A Comprehensive Study on the Sensing Characteristics of a Piezoresistive Tactile Sensor

At present, tactile sensor technology is the only solution to measure the pressure and contact area of two solid in normal contact. In this study, the sensing characteristics of a taxel inside a flexible tactile sensor were investigated for accurate contact pressure measurements with the tactile sensors. First, a tactile sensor with 64 taxels was designed and manufactured using the microfabrication techniques. Then, an electronic scanning circuit was designed to acquire the resistance change of the tactile sensor during the loading and unloading. A particular taxel was selected inside the tactile sensor to reveal the static and dynamic characteristics of the sensor. Two custom-built experimental setups were realized for the measurements. In the first experimental setup, the static characteristics of the taxel such as the repeatability, hysteresis, sensitivity and time drift were measured. Moreover, the physical sensing mechanism of the piezoresistive sensors was discussed to find the span of the force measurement. The accuracy of the taxel was found to be 5.5%. In the second experimental setup, the frequency response of the sensor was revealed for a frequency band of 0.1Hz to 40Hz. The gain of the taxel was not flat in the measured frequency band and might be used carefully in the dynamic load range after accurate calibration. Moreover, it was found that within a 48 ± 27µsec, the sensor was responsive to the impact loading using an another test set-up.