Mack Fulwyler, inventor of the cell sorter.Lab equipment is our lifeblood at BioSurplus.  We spend our days (and many nights) at the intersection of technology and the life sciences, surrounded by mass specs and microscopes, centrifuges and NMRs.  A world of sophisticated equipment that powers working research labs around the globe.

We created the Equipment Stories blog on to share our passion for lab instruments with you.  We hope you will be inspired by the amazing stories that lie behind the equipment you use in your daily quest for discovery and innovation.

This week we’d like to share the story of a dedicated physicist, inventor, and true pioneer in the field of cell analysis and flow cytometry:  Mack Fulwyler.


Los Alamos and the Invention of the Cell Sorter

Back to our question.  What do the Cold War and cell sorting have in common?

Quite a lot, it turns out.

Mack Fulwyler was born in 1936 in Nampa, Idaho.  He received his B.S. in physics from Idaho State College in 1961, and went on to serve with the U.S. Army Chemical Corps.

Jump forward to 1964 and the Los Alamos Laboratory in New Mexico.  The U.S. was entrenched in the Cold War, and Fulwyler was working for fellow physicist Marvin Van Dilla on a project to monitor fallout from atmospheric nuclear weapons testing; namely in meat, milk and other food products.

Mack Fulwyler explains:

“With the arrival of the atmospheric nuclear test ban treaty, the appearance of radioactive fallout in the diet and in humans diminished, so we had much less to do in terms of monitoring fallout.  So our group, which consisted of four individuals, three physicists, and a physical chemist, looked around to see what we could do to assist the biologists who were the other 60-some people of the group.” (Cytometry Part A, John Wiley and Sons, 2005)

He and Van Dilla began to explore their mutual interest in the Coulter counter, which Wallace H. Coulter had begun developing in 1947.

Fulwyler continues:

“We had a pathologist in our group who was using that device to analyze blood and he would adjust the aperture current and some other characteristics of the machine so that he could cause a small subpopulation of the red blood cell distribution to move away from the main distribution of red blood cells, and the pathologist thought that this represented immature RBC that had just been produced.  Well, Marvin and I did not believe that that was the case, and so we set out to try to convince him that he was incorrectly using the device, and we were not successful in doing that.” (Cytometry Part A, John Wiley and Sons, 2005)


Oscillograph + Coulter Counter = Innovation

Fulwyler believed that by sorting the cells and running them back through the Coulter counter he would be able to disprove his colleague’s data.  He then commenced to look for ways to physically isolate cells based on an electrically generated signal.

In his search he came across a paper by Dick Sweet describing an ink-writing oscillograph Sweet was developing. The device would produce a jet of ink in the air, which would then break down into droplets to be deflected onto a piece of paper.

The Original Mack Fulwyler Cell Sorter
The original electrostatic cell sorter, invented by Mack Fulwyler

Always an original thinker, Mack Fulwyler came up with the idea of combining the oscillograph with the Coulter counter.  The droplets produced by the oscillograph would serve as carriers for the cells that would then be passed through the Coulter volume sensor.

After refining his design, Fulwyler was awarded a patent for the electrostatic cell sorter in 1965.  At this time he was working for the University of California which was under contract to the Atomic Energy Commission.  The commission claimed the patent, which was subsequently licensed to Becton Dickinson.

Fulwyler described the patent thus:

“(The 1965 patent) covered the concept of analyzing a cell by any electrically convertible means and it specifically mentioned Coulter volume, fluorescence, radioactivity, means of sensing cellular characteristics, light scatter was one of them… so the basic principle said any means of sorting objects, biological and non-biological, according to an electronically extractable measurement.” (Cytometry Part A, John Wiley and Sons, 2005)


Becton Dickinson

In addition to his work as a physicist and inventor, Mack Fulwyler served as technical director at Becton Dickinson from 1977 to 1982.  While there he oversaw the development of the company’s first bench-top flow cytometer, the predecessor to the FACSCAN and the FACScalibur.

Over the course of a long and distinguished career Fulwyler served as Director of the Laboratory for Cell Analysis at UC San Francisco, Director of Technical Development at Neocrin, and as Vice President for Research and Development at DNA sequencing technology firm SEQ Ltd. in Princeton, New Jersey.  In 1998 he traveled to Europe where he conducted research as a Fulbright scholar.  Fulwyler won numerous industry and science awards, and served on the National Institutes of Health Committee on Cytology Automation.  He passed away in 2001 at the age of 65.


Becton Dickinson FACSCalibur
BD FACSCalibur in our San Diego showroom

We’ve been running a promotion on some of our flow cytometry instruments at BioSurplus in recent days.  For example, we have a complete BD FACSCalibur single laser system with computer and software in our San Diego showroom.  A Guava PCA and Guava PC are also currently available at great prices.

Take a moment to browse our catalog – if you have any questions or don’t see what you’re looking for, please contact our sales team at 858-550-0800, x201, or

Our in-house experts are on call to provide installation, service and repair, preventive maintenance, decontamination services and move management.  For more information please contact our service team at 858-550-0800 x306 or