Capacitive pressure sensor and method of making it
US4184189A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 14, 1978 |
| Grant date | Jan 15, 1980 |
| Priority date | — |
| Expiry date | Aug 14, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/43
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
An inexpensive glass capacitive pressure sensor. Conductive capacitor electrodes are disposed on two flat glass plates, one serving as a diaphragm, the other as a substrate. The electrodes are positioned in a spaced apart, substantially parallel relationship to form the plates of a parallel plate capacitor. The glass plates are sealed together with a sealing glass mixture to bound a volume between the conductors. The volume is at a reference pressure, preferably a substantial vacuum. Differences between the pressure to be measured and this reference pressure cause a flexing of the glass diaphragm which is detected by measuring the capacitance between the two electrodes. A suitable sealing glass mixture which provides a hermetic seal between the glass plates is comprised of, in weight percent, 8-10 SiO.sub.2, 1-2 Al.sub.2 O.sub.3, 55-60 PbO, 7-9 PbF.sub.2, 7-10 ZnO, 4-6 CdO, and 10-15 B.sub.2 O.sub.3. The sealing glass mixture must be vacuum fined to permit hermetic sealing within a vacuum.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.