Music Drives Samples Through New Lab-on-a-Chip

A microfluidic device, or a lab-on-a-chip, is a contraption that is able to detect certain chemicals or microorganisms in minute samples of materials that are passed through it. Experimental samples can be made to pass through it via electromechanical valves, which is the preferred method among scientists. However, experts at the University of Michigan have recently demonstrated that music can also be used for the same purpose, replacing the existing valves. Details of the find appear in the journal Proceedings of the National Academy of Sciences (PNAS), in the issue that appeared in the week of July 20th.

When the technology of microfluidic devices will develop sufficiently enough, they will become an everyday commodity. Because they combine numerous functions into a single machinery, they could be used to determine if there are any contaminants in tap water or in grocery food, or if the air conditioning is functioning properly. Their limited sizes, of a few millimeters to a few centimeters, will replace bulky laboratory equipment, and will allow home owners to bring science into their kitchens.

At this point, labs-on-a-chip are used in connection to a computer, which coordinates a vast network of air hoses, valves and electrical connections between the two devices. This allows for the splitting, merging and separation of the chemical elements making up the experimental sample.

“You quickly lose the advantage of a small microfluidic system. You'd really like to see something the size of an iPhone that you could sneeze onto and it would tell you if you have the flu. What hasn't been developed for such a small system is the pneumatics – the mechanisms for moving chemicals and samples around on the device,” UM Department of Biomedical Engineering Professor Mark Burns explains. He is also a professor and chair of the Department of Chemical Engineering at the university.

The science team managed to develop a unique pneumatic system, which makes use of musical notes to control everything that goes on inside the small channels on the chip. The notes produce varying air pressures, which are the drivers behind the action going on in the microfluidic device. “This system is a lot like fiberoptics, or cable television. Nobody's dragging 200 separate wires all over your house to power all those channels. There's one cable signal that gets decoded,” Burns says.

The main “ingredients” that have allowed for this type of accomplishment are resonance cavities, tubes of specific lengths that amplify particular musical notes inside the device itself. Each of the tubes is connected at one end to the lab-on-a-chip, and at the other end it is exposed to a speaker, powered by a computer.

“Each resonance cavity on the device is designed to amplify a specific tone and turn it into a useful pressure. If I play one note, one droplet moves. If I play a three-note chord, three move, and so on. And because the cavities don't communicate with each other, I can vary the strength of the individual notes within the chords to move a given drop faster or slower,” Sean Langelier, a UM chemical engineering doctoral student who has also been involved in the research with Burns, explains.