Development of fingertip tactile sensing chips for humanoid robots

Abstract

This paper presents the development of tactile sensing\ud chips, for the fingertips of humanoid robots. In the first phase of\ud development, piezoelectric polymer-MEA (microelectrode array)\ud based test chips have been realized. Each chip comprises of 32\ud microelectrodes, epoxy-adhered with a thin piezoelectric polymer\ud (PVDF-TrFE) film. The diameter of each microelectrode or\ud 'taxel' (tactile element) is 500 11m and the center to center\ud distance between taxels is 1 mm. The tactile sensing chips have\ud been experimentally evaluated over a wide range (0.02 - 4N or - 2\ud gmf- 400 gmt) of dynamic normal forces and frequencies (2 Hz -\ud 5 KHz) by applying variable force with constant frequency in the\ud first case and constant force with variable frequency in latter.\ud The cross-talk, among adjacent taxels on the chips, is found to be\ud approximately 20%. Finally, the ability of the chips to identify\ud object material on the basis of their hardness is also\ud demonstrated

Design and fabrication of posfet devices for tactile sensing

“…1. The experiment arrangement used to record the response of POSFET is explained elsewhere [13]. While applying force, the sensor was covered with a 300 µm thin protective PDMS (Polydimethylsiloxane) rubber.…”

Piezoelectric Tactile Sensors

“…Today, piezoelectric applications include smart materials for vibration control, aerospace and astronautical applications of flexible surfaces and structures, sensors for robotic applications, and novel applications for vibration reduction in sports equipment (tennis racquet, snowboard, etc.). Recently, the newer and rapidly burgeoning areas of application of piezoelectric materials are the nonvolatile memory (19), energy harvesting (20)(21)(22), microrobots (23), tactile skin (1,2,(24)(25)(26), and the integral incorporation of mechanical actuation and sensing microstructures into electronic chips (27)(28)(29)(30)(31)(32)(33)(34)(35)(36).…”

“…The low cost and ease of processing the polymer (compared with ceramics) have also led to its wide use as a piezoelectric material. The PVDF or its copolymers have been used in a large number of tactile sensing schemes (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(39)(40)(41)(42)(43)(44)(45). A detailed description of the piezoelectric effect is given in the following sections.…”

“…The two tactile sensor schemes developed by coupling the piezoelectric polymers with the transistors are shown in Figure 8. In these schemes, the piezoelectric polymer is present either over the gate area of the transistor (Figure 8a) (28,(31)(32)(33)(34)(35)(36) or on an extended gate as shown in Figure 8b (29,42,(53)(54)(55). The location, size, and shape of the piezoelectric polymers in these schemes may vary and accordingly the size and location of transistors too may differ.…”

Piezoelectric polymer oxide semiconductor field effect transistor (POSFET) devices for touch sensing

“…1, such a charge/vo the charge/current in the induced channel Thus, POSFET touch sensing devices direct into voltage, which can be amplified by PO further processed by an electronic circuitr present on the same chip. In this sense, POSFE device can also be compared with the mechan receptors that sense the contact parameters in and convert them into partially processed elec Somewhat similar, but with extended gat been used for the development of ultrasonic touch sensors [12]. The extended gates, epo PVDF (Polyvinylidene Fluoride) films, are works.…”