| abstract |
In this invention, a first sensor senses an organic gas, liquid or vapor and includes a first support having a first support surface with a layer of material fastened to it. In the presence of liquid, gas or vapor, the material swells and expands so as to vary at least one of its dimensions. Such expansion develops a stress at an interface between the first support surface and the material, and strain sensitive resistors detect the stress and produce an output which varies as a function of the stress at the interface. One of a pair of piezoresistors is located where there is increased stress and the other piezoresistor is disposed where there is reduced stress. If desired, a second sensor similar in structure to the first but exposed only to a reference organic liquid, gas or vapor temperature compensates the first. In another embodiment of the invention, an organic chemical responsive sensor includes a first support having a first support surface and a first capacitor plate fastened to the first support. A second support coupled to the first support spaces a second capacitor plate a distance away from the first plate. A material which expands in the presence of organic liquid, gas or vapor is applied to the first support surface so that upon expansion, the first support deflects and changes the distance between the two capacitor plates, thereby changing an electrical capacity between the plates. Another sensor of similar structure may optionally temperature compensate the first. |