A research team has done Star Trek one better, developing proof-of-concept for a technology that uses sound waves and microfluidics to sort out cells—the basis of a diagnostic device akin to the medical tricorders used by Drs. ‘Bones’ McCoy and Beverly Crusher.
The team has applied that technology to a miniature device that uses two sound waves as acoustic tweezers to assist in sorting a continuous flow of cells into five outlets on a dime-sized microfluidic chip. Researchers can alter the paths of the cells by changing the frequency of the acoustic waves.
“Our device is assembled on a low-cost and disposable microfluidic chip and requires small sample volumes (~ 100 ml), making it an ideal tool for research labs and point-of-care diagnostics,” the researchers concluded in a study published today in the journal Lab on a Chip. “It can be conveniently integrated with a small RF power supply, a fluorescent detection module, and a high-speed electrical feedback module to function as a fully integrated, portable, inexpensive, multi-color, miniature fluorescence-activated cell sorting (µFACS) system.”
The study’s lead author, Tony Jun Huang, Ph.D., associate professor of engineering science and mechanics at Pennsylvania State University, said in a statement he envisioned the device being used someday by biological, genetic, and medical labs for blood and genetic testing, among other types of diagnostic testing.
"Eventually, you could do analysis on a device about the size of a cell phone," Dr. Huang said. "It's very doable and we're making in-roads to that right now."
He said such diagnostics would be a welcome advance from current devices, which by contrast allow sorting of cells into just two channels per step, and require that cells be encapsulated into droplets, complicating analysis. Current cell sorters are also bulky and use technologies that produce gases requiring additional safety precautions.
To create their microfluidic chip, Dr. Huang and colleagues used polydimethylsiloxane, a layer of silicone, then placed two parallel transducers for converting alternating current into sound waves at the sides. Interference between the waves forms pressure nodes on the chip, to which cells are channeled as they cross the chip.
Researchers were able to adjust the frequencies and create pressure nodes on the chip because the transducers can be turned. Also adjustable is the number of channels: “We could do 10 channels if we want, we just used five because we thought it was impressive enough to show that the concept worked," Dr. Huang said.
The device was first tested by researchers sorting a stream of fluorescent polystyrene beads. The beads flowed across the chip unimpeded until the transducer was turned on, producing the sound waves that separated the particles into three channels.
Following this experiment, the researchers 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.
[Read the full study here (registration required): http://pubs.rsc.org/en/content/pdf/article/2012/lc/c2lc40751e]