New insights into cancer mechanisms from acoustic tweezer separation method

An improvement in the ability of clinicians to diagnose cancer and to understand how it spreads through the body could result from a new technique that uses sound waves to isolate cancer cells in blood samples. Developed by engineers from Penn State University, Carnegie Mellon University and MIT, the ‘acoustic tweezers’ will give doctors a low-cost method of separating cancer cells without damaging them.

In blood samples from cancer patients, typically one cell in a billion is a circulating cancer cell (CTC). “Looking for CTCs is like looking for a needle in a haystack,” said research leader Tony Jun Huang.

The acoustic tweezers use a phenomenon called tilted-angle surface acoustic waves to separate out tumour cells. This is much gentler than centrifugation, which spins the sample at 3,000rpm for ten minutes. The team used a microfluidic device to analyse the blood samples continuously, and chose acoustic pressures that would nudge the CTCs, which are heavier than blood cells, out of the stream and into a collection channel.