Miniature Ultrasonic and Tactile Sensors for Dexterous Robot

Abstract

Miniature ultrasonic and tactile sensors on Si substrate have been proposed, fabricated and characterized to detect objects for a dexterous robot. The ultrasonic sensor consists of piezoelectric PZT thin film on a Pt/Ti/SiO 2 and/or Si diaphragm fabricated using a micromachining technique; the ultrasonic sensor detects the piezoelectric voltage as an ultrasonic wave. The sensitivity has been enhanced by improving the device structure, and the resonant frequency in the array sensor has been equalized. Position detection has been carried out by using a sensor array with high sensitivity and uniform resonant frequency. The tactile sensor consists of four or three warped cantilevers which have NiCr or Si:B + piezoresistive layer for stress detection. Normal and shear stresses can be estimated by calculation using resistance changes of the piezoresitive layers on the cantilevers. Gripping state has been identified by using the tactile sensor which is installed on finger of a robot hand, and friction of objects has been measured by slipping the sensor.

Recent advances of conductive nanocomposites in printed and flexible electronics

“…The thin layers of nanocomposites behave like piezoresistive transducers as conductive channels are generated within the elastomeric matrix on application of force or pressure. Several other type of piezoresistive materials and mechanisms, which have been explored, include metallic strain gauges with different geometries and the semiconductors based materials with tuned doping levels [61][62][63]. Despite the widespread use, these materials and structures have several drawbacks compared to nanocomposite-based sensors.…”

“…Macroelectronics is the benchmark for such motivation to explore these new techniques for processing various materials and develop devices and systems which could not be realized easily by the conventional fabrication techniques on large surfaces [1,2]. In particular, the focus lies on the manufacturing processes, ease of handling of materials, compatibility of dissimilar materials in multilayer structures, overall assembly of the sensor modules and finally on the basis of sensor response to normal compressive forces [20,50,62,72,142]. Large area sensors especially the nanocomposites based piezoresistive sensors on non-planar surfaces are direly needed for its high demand in tactile force sensors and stretchability related applications [21,49,50,60,62,145,150,151].…”

“…In particular, the focus lies on the manufacturing processes, ease of handling of materials, compatibility of dissimilar materials in multilayer structures, overall assembly of the sensor modules and finally on the basis of sensor response to normal compressive forces [20,50,62,72,142]. Large area sensors especially the nanocomposites based piezoresistive sensors on non-planar surfaces are direly needed for its high demand in tactile force sensors and stretchability related applications [21,49,50,60,62,145,150,151]. The development of pressure sensors often takes the form of parallel plate structures where the nanocomposite solution is sandwiched between two metallic plates.…”