Integrated micromachined thermal mass flow sensor and methods of making the same
US7908096B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 28, 2007 |
| Grant date | Mar 15, 2011 |
| Priority date | — |
| Expiry date | Mar 31, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/698
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An integrated mass flow sensor is manufactured by a process of carrying out a micro-machining process on an N or P-type silicon substrate with orientation <100>. This mass flow sensor comprises an upstream thin-film heater, an downstream thin-film heater, and a pair of thin-film heat sensing elements, and a thermally isolated membrane for supporting the heaters and the sensors out of contact with the substrate base. This mass flow sensor is operated with three sets of circuits, a first circuit for measuring a flow rate in a first range of flow rates, a second circuit for measuring a flow rate in a second range of flow rates, and a third circuit in a differential configuration for measuring a flow rate in said first range of flow rates or said second range of flow rates, to significantly increase range of flow rate measurements and provide an optional for concentration measurement, while maintains a high degree of measurement accuracy.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.