Abstract: A gas sensing apparatus is disclosed including a gas sensing device that is self-heated due to an applied voltage, whose resistance variation amount is varied to thereby sense gas; a voltage supply for variably supplying a voltage to the gas sensing device; a current detector for detecting the current flowing through the gas sensing device thereby generating a current-voltage characteristic for the gas sensing apparatus under the effect of a given gas exposure; and a control and judgement portion for controlling the voltage supply to control a variation value of a voltage supplied to the gas sensing device and to determine the kind and density of a gas in an ambient atmosphere, using current-voltage characteristic reference data.

Abstract: A gas sensor for detecting a gas component from a food item includes a sensing layer having an electrical resistance value that varies in accordance with the concentration and type of the gas component generated from the food item to thereby sense the gas component, first and second electrodes coupled across the sensing layer and connected to a power supply, a heater for heating the gas sensor to a temperature of sensing operation, and a switch connected to an adjustable voltage supply for controlling whether the heater is operated in a first temperature range or in a second temperature range. The sensing layer includes a mixture of SnO.sub.2 and WO.sub.3 in a predetermined ratio.

Abstract: A vegetable freshness sensor production method and a freshness keeping device using the sensor are disclosed. The sensor senses gases generated by vegetables, thus to not only sense freshness of the vegetables but also sense decayed state of the vegetables. The vegetable freshness keeping device appropriately controls temperature, pressure, humidity, O.sub.2 /CO.sub.2 and quantity of anion in the vegetable store room in accordance with sensing result of the sensor, thus to keep freshness of the vegetables for a long time. In order to produce the gas sensor, a mixture of a metal catalyst and a sensing material is calcinated and mixed with an organic vehicle, thus to form a paste. The paste is coated on an electrode surface of an alumina substrate, thus to form a sensing layer on the substrate. The substrate, after being sintered, is subjected to a wire bonding and to a packaging, thus to form the gas sensor.

Abstract: A thin-film gas sensor and manufacturing method of the same is disclosed which includes a silicon substrate; an insulating layer formed on the surface of the silicon substrate; a heater formed in zigzag on the surface of said insulating layer; a temperature sensor formed in zigzag on the surface of the insulating layer in parallel with the heater; an interlayer insulating layer for electrically insulating the heater and temperature sensor formed on the insulating layer; a plurality of electrodes formed on the interlayer insulating layer placed between the heater and temperature sensor; a plurality of pairs of gas sensing layers disposed in an array on the electrodes and for reacting on detected gas; and a plurality of gas shielding layers formed on one gas sensing layer out of the pair of gas sensing layers and for shielding the detected gas so that the gas sensing layers do not react on the detected gas.

Abstract: This invention relates to a low power consumption type thin film gas sensor and method for fabricating the same. The gas sensor includes a silicon substrate having a window in the central part of one side thereof, masking material formed on the one side thereof except the window, a supporting film formed of an etch stop layer and a glass film on the other side of the substrate, heaters and temperature sensors arranged in parallel on the supporting film facing the window, an interlayer insulation film formed on the supporting film to cover the heaters and the temperature sensors, sensing film electrodes formed on the interlayer insulation film, and a sensing film formed on the interlayer insulation film so as to cover the sensing film electrodes for sensing a particular gas.