A Surgeon's Knife That Keeps Itself Steady
A new surgery tool under development compensates for the natural trembling of the human hand. It could be especially helpful for super-delicate eye or nerve surgeries, its creators say.
CREDIT: Courtesy Cheol Song, Johns Hopkins University
Surgeons have always needed to be steady-handed, but they soon may get some help from their scalpels. Researchers have created a surgical tool that compensates for the natural movement of the hand, keeping the tool tip steady for extra-delicate procedures, such as eye or nerve surgeries.
"The main objective of our research has been to make an established surgical tool 'smarter,'" Jin Kang, an engineer at Johns Hopkins University who led research on the new tool, said in a statement.
Humans are never able hold their hands perfectly still. Even the steadiest hands make nearly invisible shifts — each 50 to 100 microns long, or about the width of a human hair — several times a second. The tool uses a combination of high-speed sensors and tiny motors to detect its location and move, compensating for the natural trembling of the surgeon's hand.
The tool, which Kang and his colleagues have named SMART (Smart Micromanipulation-Aided Robotic-surgical Tool), determines its position by sending out pulses of infrared light through an optical fiber. The light, which won't harm the human eye, bounces off any tissue underneath the tool and returns to the same fiber. SMART measures motion by calculating the time it takes for the light to return. [Scientists Use Lasers to See Around Corners]
To make up for any unsteadiness, SMART shifts its tip around using small motors powered by pressure and movement. The motors are able to move accurately, as often as 500 times a second. SMART's creators tested two surgeons, finding that the doctors tended to move their hands 15 times or fewer per second when holding SMART with its motors switched off.
SMART's engineers also asked the surgeons to hold the tool as still as possible, with the tool's motors running, for five- and 30-second periods. The engineers found SMART's system helped keep the tool tip steadier.
The current prototype has a needle for a tip, but in the future, the SMART base could house interchangeable tips, allowing surgeons to use SMART assistance for several types of instruments.
Kang and his colleagues will publish a paper about SMART in the Oct. 8 issue of the journal Optics Express.