1973-02-01

The Brady Array - A New Bulk-Effect Humidity Sensor 730571

ABSTRACT

Unlike lithium chloride, chemical, and other surface-type elements, the Brady Array exhibits bulk effects conforming to the Poole-Frenkel law concerning bulk phenomena. Other types of sensors require agglomeration of water or moisture prior to measurement; in the array, measurements are accomplished at a discrete molecular level, resulting in extremely rapid response and recovery times (better than 150 ms). Stressed bonds within the structure initiate rapid recovery by purging the sensor when it is moved from higher to lower values of relative humidity.

The sensing element is contained within a TO-5 type transistor housing, measuring only 10 mil in diameter and 100 mil in length.

The array has been operated over temperature extremes ranging - 200 to +800°F without damage or loss of calibration.

The technique employed in the array also lends itself to sensing of other gases, when constructed using techniques proprietary to Thunder Scientific Corp. In-house development is in progress on array-type sensors of the major pollutants, such as CO, CO2, NO2, etc.

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