Finger-inspired Tactile Sensor for Three-axis Force Perception and Slip Detection

It is crucial for intelligent robots to acquire tactile sensing information to achieve stable grasping of objects. Rich real-time tactile information needs to be collected to improve the performance of manipulators during tactile exploration and object manipulation. However, existing tactile sensors have the relatively low spatial resolution. In this paper, a flexible tactile sensor array with
$3 \times 3$
sensing cells was proposed with high spatial resolution, which can be easily worn on the hand to obtain tactile sensing information. The proposed tactile sensor array has a finger-like three-layer structure, including a bottom information reading layer, a middle conductive layer, and a top PDMS buffer layer. Among them, the conductive layer is fabricated using polydimethylsiloxane(PDMS)/multi-walled carbon nanotubes (MWCNTs)/molybdenum disulfide
${\boldsymbol{(\text{MoS}_{2})/\text{silver}}}$
particles(Ag) composites as sensing materials. The fabricated tactile sensor array has high sensitivity and excellent stability. The sensitivity is
$1.63\times 10^{-1}\text{kPa}^{-1}$
in the low-pressure range (0–4 kPa) and
$3.96 \times 10^{-4}\text{kPa}^{-1}$
in the high-pressure range (5–143 kPa). In addition, cyclic load-unload tests reveal that the sensor is excellent stability, with the sensor maintaining its signal detection after 11,000 cycles of compression at 60 kPa pressure. Benefiting from the finger-like structure and superior performance, when grasping an object with a dummy hand fitted with an array of flexible tactile sensors, the three-axis force applied to the object can be detected and it can successfully detect slipping when grasping objects. The sensor also has the function of human health monitoring, such as monitoring human wrist pulses and carotid arteries. Therefore, the presented flexible tactile sensor array can simultaneously detect the three-axis force and slip state of the object, enabling dexterous control of the object.