Method for the non-invasive sensing of physical matter on the detection surface of a capacitive sensor
US6191593A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 17, 1997 |
| Grant date | Feb 20, 2001 |
| Priority date | — |
| Expiry date | Dec 17, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B7/004
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A capacitance sensor detects the absence/presence of physical matter on a sensing surface of the sensor. The capacitive sensor is a multi-cell sensor wherein each cell has one or more buried, protected, and physically inaccessible capacitor plates. The sensor is physically placed in an environment that is to be monitored for deposition of a particle, vapor, and/or drop of a foreign material on the sensing surface. All cells are initially placed in a startup condition or state. Thereafter, the cells are interrogated or readout, looking for a change in the equivalent feedback capacitance that results from an electrical field shape modification that is caused by the presence of physical matter on the sensing surface. When no such change is detected, the method is repeated for another cell. When a change is detected for a cell, a particle/vapor/drop output is provided. As an optional step, the sensor is provided with a layer of a material that is selectively reactive to or reactive with, a particle/vapor/drop of a known type of foreign material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.