RESUMO
An experiment was performed to calibrate the capability of a tactile sensor, which is based on gallium nitride (GaN) nanopillars, to measure the absolute magnitude and direction of an applied shear force without the need for any post-processing of data. The force's magnitude was deduced from monitoring the nanopillars' light emission intensity. Calibration of the tactile sensor used a commercial force/torque (F/T) sensor. Numerical simulations were carried out to translate the F/T sensor's reading to the shear force applied to each nanopillar's tip. The results confirmed the direct measurement of shear stress from 3.71 to 50 kPa, which is in the range of interest for completing robotic tasks such as grasping, pose estimation, and item discovery.
RESUMO
An ultrathin tactile sensor with directional sensitivity and capable of mapping at a high spatial resolution is proposed and demonstrated. Each sensor node consists of two gallium nitride (GaN) nanopillar light-emitting diodes. Shear stress applied on the nanopillars causes the electrons and holes to separate in the radial direction and reduces the light intensity emitted from the nanopillars. A sensor array comprising 64 sensor nodes was designed and fabricated. Two-dimensional directional sensitivity was experimentally confirmed with a dynamic range of 1-30 mN and an accuracy of ±1.3 mN. Tracking and mapping of an external force moving across the sensor array were also demonstrated. Finally, the proposed tactile sensor's sensitivity was tested with a fingertip gently moving across the sensor array. The sensor successfully registered the finger movement's direction and fingerprint pattern.
