Physicist developed ‘optical tweezers’
Won Nobel at 96, paved way for key advances
Arthur Ashkin, a Nobel Prize-winning physicist who harnessed the power of light to levitate particles and take hold of living cells, died Sept. 21 at home in Rumson, N. J. He was 98.
Ashkin earned the physics prize in 2018, at 96, for inventing what was dubbed “optical tweezers” more than three decades earlier.
A longtime researcher at what is now Nokia Bell Labs, Ashkin was fascinated by an often- overlooked aspect of light, which exerts a relatively weak force known as radiation pressure. After the laser was invented in 1960, he believed he might be able to use the device to push a microscopic ball with nothing but a tightly focused beam of light.
Optical tweezers uses “laser- beam fingers,” as the Nobel committee put it, to grab atoms, viruses, bacteria and other living cells. The instrument has been credited with paving the way for such advances as the development of a malaria blood test and cholesterol-lowering drugs.
Optical tweezers, Ashkin said, had enabled him to stretch and study DNA, and allowed Stanford biophysicist Steven Block to study how E. coli can tumble and swim.
Ashkin pioneered what he called “internal cell surgery,” in which researchers could use laser traps to grab and move large organelles such as nuclei and chloroplasts within the cell.
He later said he and colleague Joe Dziedzic had initially trapped living things by accident, after leaving an experiment running overnight with bacteria trapped inside.
Arthur Ashkin was born in Brooklyn on Sept. 2, 1922.
He graduated from Columbia in physics in 1947.
On the advice of his older brother Julius, a researcher on the Manhattan Project, he studied nuclear physics, receiving a doctorate from Cornell University in 1952.
His brother cast a long shadow — “I was known as ‘Ashkin’s brother Ashkin,’” he said — and the younger Ashkin switched fields in 1952 to study microwaves. He focused on lasers and nonlinear optics, before retiring in 1992.
Ashkin split the Nobel with Gérard Mourou and Donna Strickland. He was elected to the National Academy of Engineering and the National Academy of Sciences, and inducted into the National Inventors Hall of Fame in 2013.