A mono-structural thin plate touch sensor with four sensing functions for discrimination of material properties

A new mono-structural thin plate touch sensor with four sensing functions to discriminate the characteristics of materials by putting on the surface of test materials is proposed. Each of these four kinds of sensing functions, that is, a thermal sensing function, an inductive sensing function, a capacitive sensing function and a hardness sensing function in the mono-structural sensor can be realized by changing the connection of wiring between a measurement circuit and the sensor. This sensor consists of a pair of thin filamentary spiral copper wires. Each wire is evaporated on the surface of a thin insulating substrate. To investigate the sensing ability for the four sensing functions, measurements were made on eight kinds of well-known material: iron, aluminum, copper, bronze, gum, plywood, acrylic resin and styrene foam. The spiral wires of the sensor are tightly placed on the surface of each test material through a thin insulating film. It was found that the typical sample materials could be roughly separated into four kinds, that is, iron, gum, a group of plywood, acrylic reign and styrene foam, and a group of aluminum, copper and bronze. The technique of pattern recognition by multi-dimensional indication of data was adopted to discriminate material properties. This study provide some useful information for the future realization of an artificial material property recognition system in the industrial field