Fluid flow sensor with thermistor detector
US5243858A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1991 |
| Grant date | Sep 14, 1993 |
| Priority date | — |
| Expiry date | Aug 12, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/708
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An airflow sensor formed on a silicon chip comprises a silicon base covered with an insulating polyimide layer, a lineal resistance heater on the chip energized with current pulses to propagate thermal waves, and a thermistor on the chip downstream of the heater to detect the arrival of each thermal wave. Circuitry determines flow rate as a function of the measured propagation time of the thermal wave. The thermistor may be replaced by a bridge of four resistive elements of which only one or two are sensitive to the thermal wave. The thermistor material is platinum, polycrystalline silicon or amorphous silicon which exhibit high temperature coefficients of resistance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.