Acoustic 'tweezers' can hold a single cell

A device about the size of a dime uses sound waves as a sort of tweezers to manipulate living materials as small as blood cells, Penn State researchers say. The device, called acoustic tweezers, is the first technology capable of touchlessly trapping and manipulating cellular-scale objects that are essential to many areas of fundamental biomedical research, the university reported Friday. The device is based on piezoelectric material that moves in response to an electrical current, creating vibrations that are converted into standing surface acoustic waves, that in turn propagate pressure fields in the liquid medium that holds the specimen. The electronics in the device can tune the standing waves precisely and non-invasively to hold and move the specimen, researchers said. "We believe the device can be easily manufactured at a cost far lower than say, optical tweezers, which use lasers to manipulate single particles," bioengineer Tony Jun Huang said. "Optical tweezers require power densities 10 million times greater than our acoustic tweezers, and the lasers can heat up and damage the cells, unlike ultrasound." Acoustic tweezers are very versatile, Huang said. "We can manipulate a single cell or we can manipulate tens of thousands of cells at the same time."