Integrated circuit for a chemical-selective sensor with voltage output
First Claim
1. An integrated circuit for a miniaturized solid-state chemical sensor, said integrated circuit comprising:
- a semiconductor substrate;
a plurality of layers formed on said substrate so as to define a plurality of transistors configured as an amplifier, two of said transistors comprising field-effect input transistors with essentially identical dimensions and gate electrodes;
a chemical-selective membrane;
a membrane definition layer applied over said layers defining said amplifier, said membrane definition layer comprising a well for receiving said chemical-selective membrane, said well being formed in sufficient proximity to said gate electrode of at least one of said input transistors such that said chemical-selective membrane is separated from said gate electrode by no greater distance than the largest dimension of said input transistors;
means formed on said substrate for electrically connecting said chemical-selective membrane to said gate electrode of one of said input transistors; and
said gate electrode of said other input transistor being electrically connected to said output of said amplifier to provide a unity-gain buffer.
1 Assignment
0 Petitions
Accused Products
Abstract
An integrated circuit for a miniaturized solid-state chemical sensor. The integrated circuit includes a chemical-selective membrane which provides an electric signal in response to contact with a particular chemical or group of chemicals in a fluid. The chemical-selective membrane is attached to the integrated circuit by a membrane definition layer. An electrically conductive layer beneath the membrane definition layer provides electrical contact between the chemical-selective membrane and one of the input transistors of the voltage-follower amplifier. The chemical-selective membrane is formed separately from the gate of the input transistors and is designed as a integrated input to the amplifier. The output of the chemical sensor is a low impedance electric signal represented as a voltage which corresponds to the chemical activity present at the chemical-selective membrane/fluid interface. In one embodiment, multiple chemical sensors are fabricated on a single integrated circuit wherein each chemical-selective sensor forms an integrated input to a separate amplifier. Included on the integrated circuit of that embodiment is circuitry to allow for multiplexing of the outputs of the amplifiers to one or both of two output pads provided on the integrated circuit.
-
Citations
28 Claims
-
1. An integrated circuit for a miniaturized solid-state chemical sensor, said integrated circuit comprising:
-
a semiconductor substrate; a plurality of layers formed on said substrate so as to define a plurality of transistors configured as an amplifier, two of said transistors comprising field-effect input transistors with essentially identical dimensions and gate electrodes; a chemical-selective membrane; a membrane definition layer applied over said layers defining said amplifier, said membrane definition layer comprising a well for receiving said chemical-selective membrane, said well being formed in sufficient proximity to said gate electrode of at least one of said input transistors such that said chemical-selective membrane is separated from said gate electrode by no greater distance than the largest dimension of said input transistors; means formed on said substrate for electrically connecting said chemical-selective membrane to said gate electrode of one of said input transistors; and said gate electrode of said other input transistor being electrically connected to said output of said amplifier to provide a unity-gain buffer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. An integrated circuit for a miniaturized solid-state chemical sensor adapted to sense one or more selected chemicals in a fluid, said integrated circuit comprising:
-
a semiconductor substrate; a plurality of layers formed on said substrate so as to define a plurality of transistors interconnected to form a plurality of voltage-follower amplifiers, each said amplifier comprising a pair of field-effect input transistors having essentially identical dimensions and gate electrodes; a membrane definition layer applied over said layers defining said amplifiers; a plurality of chemical-selective membranes held by said membrane definition layer, each said membrane being secured to a region of said membrane definition layer so as to be essentially immediately adjacent the gate electrode of a corresponding input transistor; a metal layer formed between said membrane definition layer and said plurality of layers defining said transistors, said metal layer comprising a series of electrical contact locations providing electrical contact between each said chemical-selective membrane and the gate electrode of one of said input transistors of a corresponding amplifier for said chemical-selective membrane; and said plurality of layers further defining means formed on said substrate for outputting an electrical signal from at least one of said amplifiers, and means for selectively switching from one of said amplifiers to another so as to be able to selectively connect an output voltage from any said amplifier to said means for outputting said electrical signal. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
-
Specification