HANDHELD gadgets could one day diagnose infections at the push of a button by using the supersensitive touchscreens in today鈥檚 smartphones.
Many believe that in the future collecting samples of saliva, urine or blood could be performed using a cheap, USB-stick-sized throwaway device called a lab-on-a-chip. The user would inject a droplet of the fluid in the chip, and micropumps inside it would send the fluid to internal vessels containing reagents that extract target disease biomarker molecules. The whole device would then be sent to a lab for analysis.
But Hyun Gyu Park and Byoung Yeon Won at the in Daejeon think touchscreens could improve the process by letting your phone replace the lab work. Park suggests the lab-on-a-chip could present a tiny droplet of the sample to be pressed against a phone鈥檚 touchscreen for analysis, where an app would work out whether you have food poisoning, strep throat or flu, for example.
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聯An app could work out whether you have food poisoning, strep throat or flu, for example聰
The idea depends on a method the pair have devised to harness the way a touchscreen senses a fingertip鈥檚 ability to store electric charge 鈥� known as its capacitance. The capacitive sensitivity of touchscreens is far higher than what is needed to sense our fingers as we play games or tap out tweets. 鈥淪ince these touchscreens can detect very small capacitance changes we thought they could serve as highly sensitive detection platforms for disease biomarkers,鈥� says Park.
So the pair began proof-of-concept tests to see if the touchscreens in our pockets could play a role in diagnosing our ailments. First they took three solutions containing differing concentrations of DNA from the bacteria that causes chlamydia and applied droplets from each to an iPhone-sized multitouch display. They found that the output from the screen鈥檚 array of crisscrossed touch-sensing electrodes could distinguish between the capacitances caused by each concentration using droplets of only 10 microlitres (Angewandte Chemie International Edition, ).
The technology is not yet able to identify individual pathogens but Park sees the display鈥檚 ability to differentiate between concentrations as a first step towards this.
However, before the idea can be rolled out the built-in software on touchscreens that eliminates false-touch signals caused by moisture or sweat would need modifying. Park also plans to develop a film that can be stuck on a touchscreen to which the biomarkers will attach. 鈥淣obody wants direct application of bio-samples onto their phone,鈥� he says.
鈥淭his is potentially possible,鈥� says Harpal Minhas, editor of the journal Lab On A Chip. 鈥淏ut any changes to current production-line touchscreens would need to demonstrate huge financial benefits before they are implemented.鈥� And DNA sequencing, rather than concentration measurement, is more likely to be necessary for disease diagnosis, he adds.
