Science Fiction in the Making: Miniature Medical Device Based on Sound Tech

Very soon a miniature medical diagnostic device will be created based on acoustic waves technique to sort cells on a chip. This device uses two beams of acoustic or sound waves.

According to the researchers this new device could make Star Trek's tricorder seem a bit bulky in comparison.

"The device uses two beams of acoustic or sound waves to act as acoustic tweezers and sort a continuous flow of cells on a dime-sized chip," said Tony Jun Huang, associate professor of engineering science and mechanics, Penn State. 

Huang worked with Xiaoyun Ding, graduate student, Sz-Chin Steven Lin, postdoctoral research scholar, Michael Ian Lapsley, graduate student, Xiang Guo, undergraduate student, Chung Yu Keith Chan, doctoral student, Sixing Li, doctoral student, all of the Department of Engineering Science and Mechanics at Penn State; Lin Wang, Ascent BioNano Technologies; and J. Philip McCoy, National Heart, Lung and Blood Institute, National Institutes of Health.

The paths of the cells can be easily altered by changing the frequency of the acoustic waves.

According to Hugh, since the device can sort cells into five or more channels it permits more cell types to be analyzed. And this gives way for smaller and efficient, less expensive analytical device.

"Eventually, you could do analysis on a device about the size of a cell phone," said Huang. "It's very doable and we're making in-roads to that right now."

"Biological, genetic and medical labs could use the device for various types of analysis, including blood and genetic testing," Huang said.

He stated during the study that most of the current cell-sorting devices allow the cells to be sorted into only two channels in one step. The set back of current cell sorting devices is that the cell must encapsulate into droplets.

"Today, cell sorting is done on bulky and very expensive devices," said Huang. "We want to minimize them so they are portable, inexpensive and can be powered by batteries. Using sound waves for cell sorting is less likely to damage cells than current techniques."

In addition to the inefficiency and the lack of controllability, current methods produce aerosols, gases that require extra safety precautions to handle.

They created the acoustic wave cell sorting chip using a layer of silicone known as polydimethylsiloxane.

According to Huang, "Two parallel transducers, which convert alternating current into acoustic waves, were placed at the sides of the chip. As the acoustic waves interfere with each other, they form pressure nodes on the chip. As cells cross the chip, they are channeled toward these pressure nodes."

Since the transducers are tunable the researchers were able o adjust the frequencies and create pressure nodes on the chip. They first tested the device by sorting a stream of fluorescent polystyrene beads into three channels. Prior to turning on the transducer, the particles flowed across the chip unimpeded. Once the transducer produced the acoustic waves, the particles were separated into the channels.

The researchers also sorted human white blood cells that were affected by leukemia. The leukemia cells were first focused into the main channel and then separated into five channels.