Company History

The growth and innovations of Grass Instrument, founded by Albert Grass who developed the first commercially successful electroencephalograph (EEG), may be of interest to those interested in the history of neurophysiology, EEG and polysomnography (PSG).

The following is a chronology of the beginnings of EEG/PSG technology, and consequently, of Grass Instrument Company.

1934: A small grant is awarded to Dr. Frederic Gibbs for instrumentation to process electroencephalographic data. His goal is to apply the knowledge gained by Hans Berger and confirmed by Lord Adrian to clinical applications.

1935: Dr. Gibbs approaches Albert Grass, a recent graduate of MIT, to design three devices to amplify human EEG potentials. Grass does so, defining the foundation of Grass Instrument Company, and of EEG technology.

1936: While working at Harvard Medical School, Grass designs moving coil galvanometers, which enables the embryonic EEG instrumentation to accurately and reliably record the EEG frequencies on chart paper. The addition of these new galvanometers to his early amplifiers becomes the Grass Model I, used by Gibbs, Lennox, Davis and others. This same amplifier design was used by Cannon, Rosenbluth and Renshaw in early neuromuscular studies.

Grass Model I

1938: A two-channel Grass Model I EEG is used by Dr. Hallowell Davis to record and report more detailed steps in the awake-sleep transition; named the "K" complex, a high voltage diphasic slow wave associated with a sleep spindle.

1938: Grass Model II is developed and used by doctors to evaluate head injuries and the condition of airplane pilots as World War II begins in Europe.

1946: The post-war development and production of the Grass Model III begins, which sets the standard for ease of use, sturdy design, and system safeguards, that endures among Grass EEGs today.

1947: Grass begins development of an electrical stimulator to aid in mapping the human cortex.

1948: Grass improves the design and production of electrodes and develops a cortical electrode array for electrocorticography, still in use today.

1950: Dr. Nathaniel Kleitman uses the Grass Model III in his ground breaking research on REM sleep. This is the first time an accurate recording is made of rapid eye movements in sleep.

1950: Dr. Frederic Gibbs & Erna Gibbs, used an eight-channel Grass Model III EEG, first emphasized age-related differences in the sleep onset EEG and separated the adult type from that of children.

1950s: Grass Model 5 Polygraphs are used to record a wide range of physiological and pharmacological parameters in animal research laboratories all over the world and they are introduced in student laboratories of major medical schools for "hands on" teaching exercises. Grass designs an oscilloscope kymograph recording camera that photographs the oscilloscope traces on photosensitive film and paper, and faithfully captures fast transient neurophysiological events.

1955: Albert Grass establishes the Grass Foundation to promote and foster research and education in neurophysiology. To date, the Foundation has provided funding for the Marine Biological Laboratory (MBL) at Woods Hole, Massachusetts and grants for over 400 MBL research fellows in neurophysiology. One such fellow was a member of a NASA space shuttle mission.

1957: Dr. W.C. Dement, Dr. Nathaniel Kleitman, used Grass Model III EEG, while reporting EEG patterns associated with REM and dreaming, redefined the stages of sleep. They defined Stage 1 REM, associated with a high percentage of dream recalls by the subjects, as having no essential EEG differences from Stage 1 non-REM except for the presence of characteristic eye movements. It was Dr. Eugene Aserinski and this group that first recorded the eye movements using electrodes placed above and below the eye. Prior to this, it was necessary for researchers to observe the eye lids to detect REM.

1960s: Grass pioneers the development of computer-compatible medical devices with the design of EEG and Polygraph systems with outputs designed for computer interface.

1970 to 1994: Grass develops clinical and research EEGs with greater numbers of channels and the capacity to interface with data processing instruments. Grass Models 8 and 9 have the capacity to perform dual EEG and PSG functions. Model 78 PSG sets the watermark in modern sleep studies. Clinical Sleep Disorders recordings demand more flexibility in the recorders to accommodate the recording of EMG, EOG, ECG, upper airway airflow and respiratory effort, limb movements, oxygent saturation. The Grass Model 78 PSG meets the demand by offering AC and DC amplifiers and special plug-ins for interfacing various analyzers

1994 to 2012:
In 1994,
Grass Instrument Co. is acquired by Astro-Med, Inc. The Model 15 line of digitally controlled amplifiers is introduced. The digital EEG and digital PSG are introduced, named the Albert Grass Heritage® to honor the founder, along with the Heritage Portable PSG. New single-channel amplifiers along with PolyVIEW™ and Gamma™ data acquisition software are introduced.

In 1999, Astro-Med also acquires Telefactor Corp., adding long-term epilepsy monitoring instrumentation, with seizure and spike analysis software to the existing line of Grass clinical products.

A steady stream of new products for research and clinical applications continue to be issued from the Grass Technologies, including ambulatory PSG systems and digital video and audio software.

2013 to Present:
In 2013, Grass Technologies is acquired by Natus Neurology and is continuing its long history of providing high quality instrumentation to the neurophysiological field.