High frequency measuring circuit with inherent noise reduction for resonating chemical sensors
US6222366A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 10, 1999 |
| Grant date | Apr 24, 2001 |
| Priority date | — |
| Expiry date | May 10, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/0426
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The concentration of an analyte in a fluid is measured by a quartz crystal microbalance sensor device in the fluid containing a concentration of the analyte. The sensor device exhibits a resonant frequency representative of the concentration of the analyte in the fluid. A quartz crystal microbalance reference device has a resonant frequency lower, by a predetermined amount, than the initial resonant frequency of the sensor device before the sensor device is exposed to the analyte. A signal is derived based on the difference of the resonant frequencies of the sensor and the reference device, and a first counter counts a predetermined number of cycles of the difference signal frequency to derive a sample time period. A second counter counts cycles of a clock signal frequency during the sample time period to derive a count representative of the difference signal frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.