Ir sensor using functional semiconducting fiber and application to human detection

Abstract

The infrared (IR) sensor has recently become more important in many fields, and development of a conventional IR sensor with a fast IR response is needed. Both SiC fiber and carbon fiber have been found to be therm-stor materials that have rapid thermal response. The present paper reports on the development of fibers for use in IR sensors, including the measurement of the fundamental fiber properties and thermal response characteristics to the IR radiation of IR sensors using fibers. Application in intelligent IR sensors, human body detection, and future developments are also reported. The IR response was affected markedly by fiber structure. A thermal time constant of 1.24 ms was observed in response to IR radiation from a 600-K black-body furnace. The thermistor constant of the fiber increased linearly with an increase in the electrical resistivity of the fiber; the output voltage of the IR sensor using a semiconducting fiber increased with an increasing thermistor constant. The IR sensor using functional semiconducting fiber with a larger thermistor constant detected intelligently in a room-temperature environment both an immobile and a mobile human body, each of which had body temperatures that were lower and higher than the room temperature. The functional semiconducting fiber was found to be a promising material for intelligent IR sensor.