Measuring and testing – Gas analysis – Detector detail
Patent
1995-11-02
1997-01-07
Williams, Hezron E.
Measuring and testing
Gas analysis
Detector detail
73 2901, 324453, 324459, G01N 2762, G01N 2752, G01T 118
Patent
active
055918964
ABSTRACT:
Solid state gas sensors are provided, the use of which permits quantitative measurement of gaseous contaminants or change of composition of a gas or atmosphere being monitored. The gas sensor comprises at least a base, a first electrode, a second electrode. The first electrode has a finely tapered end to strengthen the electric field intensity in the gap between the first and the second electrodes. The sensing is based on ionization potential difference between the molecules of the contaminating gas and of the atmosphere. When a high voltage is applied to the electrodes, it creates a strong electric field between the electrodes, especially a very strong electric field around the tapered end of the first electrode. When the potential is sufficiently high, the gas in the vicinity of the tapered end of the first electrode will be ionized. The ions and electrons generated by the ionization create an electric current flows between the two electrodes and across the gap. The changes of this electric current with gas contamination or changes in the gas composition are used as sensing signals. Unlike other gas sensors, there is no chemical reaction, absorption or adsorption involved in this sensing process. The gas sensors of this invention may be manufactured by lithographic micromachining techniques at very low cost, and they can be easily integrated with controller and signal processing circuits to upgrade to smart microsensors. Further, in an alternative embodiment, a micro-actuator to control the gap between the two electrodes is integrated with the sensors. In another alternative embodiment, a third electrode may be mounted so as to control the intensity of the electric field.
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Wiggins J. David
Williams Hezron E.
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