Chemical-sensitive field-effect transistor
First Claim
1. A field-effect transistor device for measuring a chemical property of a substance to which the device is exposed, comprising:
- a semiconductor substrate;
a source region in contact with the substrate and located near a first surface of the substrate;
a drain region in contact with the substrate, located near the first surface of the substrate and spaced apart from the source region;
a gate insulator which overlies a first area of the first surface of the substrate between the source and drain regions;
three electrodes for providing a separate electrical connection to the source region, drain region, and gate insulator; and
a layer of chemically sensitive material which overlies a second area of the substrate separate from the first area and which has an active surface for exposure to the substance, said chemically sensitive material connected in series with the substrate and located on the opposite side of the substrate from the gate insulator, said second area located sufficiently near the source and drain regions so that exposure of the chemically sensitive material to the substance results in a change of the electrical conductance between the source and drain regions.
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Abstract
The invention relates to an insulated-gate field effect transistor which is adapted for detecting and measuring various chemical properties such as ion activity in a solution. The device has a chemically sensitive layer which overlies a portion of a substrate other than that covered by the gate insulator. When this chemically sensitive layer is exposed to a solution or other substance, the electric field in the substrate is modified which changes the conductance of the channel between a source region and a drain region. The change in conductance is related to the chemical exposure and can be detected with a current meter.
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Citations
10 Claims
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1. A field-effect transistor device for measuring a chemical property of a substance to which the device is exposed, comprising:
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a semiconductor substrate; a source region in contact with the substrate and located near a first surface of the substrate; a drain region in contact with the substrate, located near the first surface of the substrate and spaced apart from the source region; a gate insulator which overlies a first area of the first surface of the substrate between the source and drain regions; three electrodes for providing a separate electrical connection to the source region, drain region, and gate insulator; and a layer of chemically sensitive material which overlies a second area of the substrate separate from the first area and which has an active surface for exposure to the substance, said chemically sensitive material connected in series with the substrate and located on the opposite side of the substrate from the gate insulator, said second area located sufficiently near the source and drain regions so that exposure of the chemically sensitive material to the substance results in a change of the electrical conductance between the source and drain regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification