In medicine, plasma usually refers to the liquid component of blood. Now scientists are researching how to better harness the plasma found in stars and lightning—the fourth fundamental state of matter, alongside solids, liquids and gases—to cut into the body like a blowtorch for bloodless surgery.

Since the early 20th century, surgeons have used sparks of plasma to zap warts and other malignant tissues. Late in that century researchers began investigating how jets of plasma might be used to carve up flesh just as industrial plasma cutters have carved up metal since the 1960s. These plasma scalpels would cauterize flesh as they slice. “It's like a lightsaber,” says Washington, D.C., surgeon Jerome Canady, who invented one of the first surgical plasma cutters.

Internal bleeding can be lethal, and finding ways to prevent it can be potentially lifesaving. Minimizing the need for blood transfusions can also be vital, especially on the battlefield—U.S. Special Operations Command field-tested surgical plasma knives in 2008.

A plasma cutter works by streaming pressurized gas such as argon through a narrow channel, where it acquires an electrical charge, transforming it into a blade of plasma traveling more than 1,500 miles per hour. Surgical plasma cutters typically use relatively cold plasmas, hot enough to cauterize tissue on direct contact but only heat surrounding cells to about 97 degrees Fahrenheit. “We can get it more precise than a scalpel blade,” Canady says. “You get 0.4 to 0.8 millimeter [0.02 to 0.03 inch] of collateral damage with conventional scalpels, but just 0.1 to 0.2 millimeter [0.004 to 0.008 inch] with plasma cutters.”

Increasingly, research suggests that plasma can have therapeutic effects beyond those from heat. Plasma causes the neutrally charged oxygen and nitrogen molecules in the air to become electrically charged. The elements then form ozone, nitrogen oxide and other reactive compounds that can kill off bacteria and cancer cells. Plasma physicist Michael Keidar, director of the George Washington Institute for Nanotechnology in Washington, D.C., and his colleagues have a five-year, $445,000 grant to investigate the physical effects of plasma on the body. Perhaps controlling the frequency, voltage and waveform of the electrical pulses used to energize the plasma affects the depth to which it penetrates living tissue. Such knowledge could help make cuts even more precise and optimize plasma cutting's antibacterial and anticancer effects. “There's been no basic research into this application of plasma,” Keidar says. “We hope a full understanding of the mechanisms of what plasma does will open a lot of doors.”