A new cilia-covered chip could revolutionize portable medical diagnosis
Now researchers have come close to doing so, creating a chip covered with artificial cilia that can precisely control the minuscule flow patterns of fluids.
Humans have achieved spectacular large-scale engineering feats, but "We are still kind of stuck when it comes to engineering miniaturized machines," says Itai Cohen, a Cornell University physicist and senior author of a new Nature study describing his team's cilia chip.
Researchers had previously tried to make artificial cilia that worked by means of pressure, light, electricity and even magnets.
Next, the researchers had to figure out how to pattern a surface with thousands of their artificial cilia.
To direct a droplet to flow in a more complex pattern, the researchers had to divide their chip's surface into "Ciliary units" of a few dozen cilia each-with each unit individually controllable.
The Cornell team first planned a control system virtually, collaborating with University of Cambridge researchers to digitally simulate in three dimensions how a droplet would move over a cilia-covered chip.
Their centimeter-wide chip is carpeted with about a thousand tiny platinum-titanium strips, divided into 16 ciliary units of 64 cilia each.
The study "Elegantly enlightened us about how independent, addressable control of artificial cilia arrays could be realized via electronic signals to generate complex programmable microfluidic operations," says Zuankai Wang, a microfluidics researcher at the City University of Hong Kong, who was not involved in the new study.
A user would place a drop of blood or urine on the chip, and the artificial cilia would carry the sample-along with any chemicals or pathogens within it-from one spot to another, allowing it to mix and react with various testing agents as it moves.
Biosensors built into the chip would measure the products of these chemical reactions and then direct the cilia to further manipulate the liquid's flow, allowing the chip to perform additional tests to confirm the results.