Lucien Vidie, French scientist, invented and built the aneroid barometer, which uses a spring balance instead of a liquid to measure atmospheric pressure. The spring extension under pressure is mechanically amplified on an indicator system. Employing the indicator method of Vidie, Eugene Bourdon (founder of the Bourdon Sedeme Company) patented the Bourdon tube pressure gauge for higher pressures in 1849
Electrical Measurement Technologies
1930
The first pressure transducers were transduction mechanisms where the movement of diaphragms, springs, or Bourdon tubes is part of an electrical quantity. Pressure diaphragms are a part of a capacitance, the indicator is the tap of a potentiometer
1938
The bonded strain gauges were independently developed by E.E Simmons of the California Institute of Technology and A.C. Ruge of Massachusetts Institute of Technology. Simmons was faster applying for a patent.
1955
The first foil strain gauges came up with an integrated full resistor bridge, which, if bonded on a diaphragm, see opposite stress in the center and at the edge.
1965
The bonding connection of the gauges to the diaphragm was always the cause for hysteresis and instability. In the 1960’s Statham introduced the first thin-film transducers with good stability and hysteresis. Today, the technology is a major player on the market for high pressure.
1973
William R. Poyle applied for a patent for capacitive transducers on glass or quartz basis, Bob Bell of Kavlico on ceramic basis a few years later in 1979. This technology filled the gap for lower pressure ranges for which thin-film was not suited. Today, it is the widest spread technology for non-benign media.
The Sensor Age
1967
Honeywell Research Center, Minneapolis, USA: Art R. Zias and John Egan applied for a patent for the edge-constrained silicon diaphragm. In 1969, Hans W. Keller applied for a patent for the batch-fabricated silicon sensor. The technology is profiting from the enormous progress of IC-technology. A modern sensor typically weighs 0.01 grams. If all non-crystalline diaphragms have inherent hysteresis, the precision limit of this item is not detectable by today’s means.
2000
The piezoresistive technology is the most universal one. It applies for pressure ranges from 100mbar to >1500 bar in the absolute, gauge, and differential pressure mode. The slow spread of the technology in high-volume applications for non-benign media resulted from the inability of US-companies to develop a decent housing. In 30 years, KELLER has perfected it at costs comparable to any other technology.
