Apparatus and method for operating an ISFET at multiple drain currents and gate-source voltages allowing for diagnostics and control of isopotential points
US5911873A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 2, 1997 |
| Grant date | Jun 15, 1999 |
| Priority date | — |
| Expiry date | May 2, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/4148
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for measuring ion concentration of a solution includes an ion sensitive field effect transistor (ISFET), a reference device, an ISFET control circuit, a memory, a measurement circuit and a diagnostic circuit. The ISFET has a drain, a source, an ion sensitive gate region and a plurality of device characteristics. The reference device is separated from the gate region by a sample solution. The ISFET control circuit is coupled to the ISFET and operates the ISFET at a drain-source voltage V.sub.DS and at n successive drain currents I.sub.Di and corresponding gate-source voltages V.sub.GSi, wherein i is an integer from 1 to n and n is an integer greater than 1. The memory stores the plurality of device characteristics and the n successive drain currents I.sub.Di and gate-source voltages V.sub.GSi. The measurement circuit measures ion concentration of the solution as a function of at least one of the n successive drain currents I.sub.Di and gate-source voltages V.sub.GSi and the plurality of device characteristics stored in the memory. The diagnostic circuit measures at least one of the device characteristics of the ISFET as a function of the n successive drain currents I.su…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.