Fluid concentration detecting apparatus
US5585729A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 1993 |
| Grant date | Dec 17, 1996 |
| Priority date | — |
| Expiry date | May 13, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/023
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus is disclosed for determining the concentration of a fluid. In one aspect of the invention an apparatus for detecting the ionic concentration of a fluid is provided. The ionic concentration detecting apparatus may include a resonance coil or other suitable receiver that arranged to be influence by the fluid being monitored. The resonance coil is driven by a high frequency signal having a frequency in the range of 10-100 MHz. A detector is provided to measure the losses experienced by the resonance coil. In another aspect of the invention, an ultrasonic based density detecting apparatus for detecting the density of the fluid is provided. The ionic concentration detecting device may be used in conjunction with the density determining device to provide concentration detecting capabilities for solutions having multiple constituents. One particularly beneficial application of the invention is for determining the concentration of an acidic solution used in a wafer wet cleaning step of a semiconductor fabrication process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.