Accelerometers by Brüel & Kjær

History of the Piezoelectric Accelerometer

The World’s first commercial piezoelectric accelerometer was developed by Dr. Per V. Brüel in 1943. However, this was only the first of many innovations, that would shape the world of test and measurement, we know today. Explore the great history of the piezoelectric accelerometer, and the many innovations that followed, solidifying Brüel & Kjær as the the primary source of sound and vibration measurement technology.

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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. 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.

Located in Nærum, Denmark, Brüel & Kjær started the sound and vibration journey in the distant 1942. The company was founded by two young university graduates, Per V. Brüel and Viggo Kjær.

With a humble start with a small, voltmeter product line, they expanded the product range over the years, which today consists of over 200 instruments, transducers, and analysis software.

Accelerometer Innovation Since 1943

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. 
 
It's no understatement to say, that Brüel & Kjær is responsible for many of the technologies used in today's sensors and transducers. 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 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
1/8-inch pressure-field microphone Type 4138

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
1-inch laboratory standard microphone Type 4160

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 Type 4155

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 1-inch low noise microphone Type 4179

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 Type 4182

World’s first accelerometer with constant voltage line‐drive (CVLD) built‐in preamplifier

    Type 4390 - World's first constant voltage accelerometer
1985 Type 8317 ½-inch free-field microphone Type 4188

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
½-inch free-field microphone Type 4189

World’s first dedicated modal shear accelerometer family

    Type 4507 - World's first modal accelerometer
1998 Type 4506 Acoustic calibrator - Type 4297

The world’s first OrthoShear™ triaxial accelerometer – one seismic mass for optimized noise floor and orthogonality

    Type 4506 - World's first OrthoShear™ triaxial accelerometer
1999 Type 4507‐B 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 Automotive surface microphone with 1 coaxial cable Type 4949

The first miniature triaxial accelerometer with integrated TEDS

    Type 4524‐B - World's first miniature TEDS accelerometer
2008 Type 4526 Outdoor microphone for noise monitoring terminals Type 4952

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 ½"" low-noise microphone system Type 4955

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 Multi-field microphone Type 4961

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 Type 1706

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
Measurement cloud

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.

World's first accelerometer made in 1943On the left: Prototype drawings of Type 4301. On the right: Photo of the actual accelerometer.

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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.