US 5,394,735 AGranted

Gas sensor

AssigneeNational Science Council

InventorsYen-Kun Fang, Bao-Chsun Fang, Jiann-Ruey Chen, Fu-Yuan Chen

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Abstract

A gas sensor having a large operation current and being operated at a relatively low temperature includes a substrate having a first surface and a second surface. A sensing area is provided on the first surface for increasing the conductivity across it when the sensing area detects a certain gas. A controlling area is provided on the first surface and beside the sensing area for permitting a tunneling current to pass therethrough when the sensing area cannot sense a certain gas or when the gas sensor is adapted to be sufficiently supplied with power. This control area prevents the tunneling current from being generated when the sensing area detects certain gas and thus the conductivity is increased, so that when the first and the second surfaces are electrically connected to the power supply. The gas sensor will be in an on state when the gas sensor cannot sense there is the certain gas and be in an off state when the gas sensor detects the presence of certain gas. This gas sensor can avoid a dangerous explosion resulting from a flammable gas at a relatively high temperature. The gas sensor possesses a relatively short response time.

Claims18

Dependent claims

A gas sensor to be powered by a power supply comprising:

a substrate having a first surface and a second surface;
a sensing area provided on said first surface and in serial relationship with said first surface, said sensing area having a variable conductivity which will increase when said sensing area senses the presence of a certain gas;
and
a controlling area provided on said first surface, said controlling area being in serial relationship with said first surface and in parallel relationship with said sensing area said controlling area being adapted to allow a tunneling current to pass therethrough when said sensing area does not detect the presence of said certain gas and when said gas sensor is sufficiently power-supplied by the power supply, said controlling area being further adapted to prevent said tunneling current from passing therethrough when said sensing area senses the presence of said certain gas and thus said conductivity of said sensing area is increased, whereby when said first and said second surfaces are electrically connected to the power supply, said gas sensor will be in a turned-on state when said gas sensor does not detect the presence of said certain gas, and will be in a turned-off state when said gas sensor detects the presence of said certain gas.

1 more element

Dependencies are inferred from the claim text.