History of the Piezoelectric Accelerometer

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ACCELEROMETER SENSORS

It’s no exaggeration to say that the entire discipline of sound and vibration can be traced to these and other innovations developed by Per Brüel and his partner Viggo Kjær. Located in Nærum, Denmark, Brüel & Kjær started the sound and vibration journey in the distant 1942.

These early innovations created the foundation for the many sound and vibration measurement technologies used to develop and monitor everything from smartphones, cars, washing machines and aircrafts, we use today.

From a humble start with a small, voltmeter product line, Brüel & Kjær quickly expanded the product range over the years, which today consists of over 200 measuring instruments, transducers, and analysis software.

Accelerometer Innovation Since 1942

Type 4301 was only the first in a long line of world's first innovative technologies to be released, but before we get to how the first commercial accelerometer ever made, let's take a closer look at some of the many technology innovations, that Brüel & Kjær has developed.

The table below gives a complete overview of the ground-breaking technological inventions, which are still used in test and measurement applications world-wide.

1943	Type 4301		World’s first commercial piezoelectric accelerometer made from Rochelle salt crystals and developed by Dr. Per V. Brüel in 1943. Type 4301 - World's first accelerometer
1957	Type 4310		A strong piezoelectric effect was discovered in lead zirconate titanate (PZT) by Jaffe in the early of 1950s, leading to the release of Brüel & Kjær’s first lead zirconate titanate (PZT) accelerometer
1971	Type 8305		Brüel & Kjær’s standard reference accelerometer based on an inverted, centremounted compression design with quartz crystal piezoelectric element, ensured a high degree of accuracy for calibration Type 8305 - Standard reference accelerometer
1974	Type 4366		This all‐titanium accelerometer was the first based on Brüel & Kjær’s patented DeltaShear™ design. Still in use today, the construction is regarded as one of the all‐time, classic accelerometer constructions Type 4366 - World's first DeltaShear™ based titanium accelerometer
1977	Type 4374		The first miniature accelerometer with a PlanarShear design – extending the frequency range of Brüel & Kjær Shear design Type 4374 - The first miniature, PlanarShear accelerometer
1985	Type 4390		World’s first accelerometer with constant voltage line‐drive (CVLD) built‐in preamplifier Type 4390 - World's first constant voltage accelerometer
1985	Type 8317		Brüel & Kjær’s first and highly reliable industrial DeltaShear accelerometer suitable for permanent vibration monitoring in potentially explosive environments Type 8317 - The first DeltaShear accelerometer
1996	Types 4507 and 4508		World’s first dedicated modal shear accelerometer family Type 4507 - World's first modal accelerometer
1998	Type 4506		The world’s first OrthoShear™ triaxial accelerometer – one seismic mass for optimized noise floor and orthogonality Type 4506 - World's first OrthoShear™ triaxial accelerometer  (N/A)
1999	Type 4507‐B		Another world first – an accelerometer with integrated TEDS (transducer electronic data sheet) Type 4507‐B - World's first TEDS accelerometer
2005	Type 4524‐B		The first miniature triaxial accelerometer with integrated TEDS Type 4524‐B - World's first miniature TEDS accelerometer
2008	Type 4526		A ThetaShear™, CCLD accelerometer for applications up to 180 °C (356 °F) – the highest temperature for an accelerometer with built‐in preamplifier in the industry Type 4526 - Accelerometer with the highest temperature in the industry
2012	Type 8347‐C		Wide temperature range (–321 to +900 °F (–196 to +482 °C)) industrial accelerometer with superior temperature transient performance from Shear design Type 8347‐C - Accelerometer with temperature range
2012	Type 4527		This universal CCLD triaxial accelerometer never sits still on the shelf, and has the widest temperature (up to 180 °C (356 °F)) and dynamic range Type 4527 - Accelerometer with the widest temperature range
2015	Type 4527‐C		The first triaxial charge accelerometer featuring a single connector Type 4527‐C - The first single connector accelerometer
2015	Types 4535‐B, 4524‐B and 4508‐B		Some of the first accelerometers with data matrix. Used with Transducer Smart Setup for seamless transfer of transducer data to PULSE Reflex™ Types 4535‐B, 4524‐B and 4508‐B - The first accelerometers with data matrix

The World's First Commercial Accelerometer

In the year 1943, Per V. Brüel designed the world’s first commercial piezoelectric accelerometer called Type 4301. It was made from Rochelle salt crystals and featured a sensitivity of 35–50 mV/g and a resonant frequency of 2–3 kHz.

On the left: Prototype drawings of Type 4301. On the right: Photo of the actual accelerometer.

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TRANSDUCERS 

Throughout the 1950s the Rochelle salt crystals were replaced by ceramic elements. This resulted in a doubling of the accelerometer’s sensitivity and increased its resonance to 5kHz.

Later, Brüel & Kjær added compression type accelerometers to its product line, which were further modified in 1964. This resulted in the introduction of a new series with reduced susceptibility to case loading and base strain. Further improvements in the compression design were made from 1968 to 1975.

Transducer development and innovation is very much in the Brüel & Kjær DNA. Today, we lead the industry with our many patented technology and unrivalled accuracy.