New sensor inspired by origami
15 Mar 2012 by hhwdjwbphm.d hhwdjwbphm.d
Inspired by origami – the Japanese art of paper folding – American chemists have developed a point-of-care sensor that could diagnose malaria and HIV in the developing world for less than 10 cents a test.
One-dimensional paper sensors are already available in pregnancy tests for example, but have their limitations. The new 3D sensors developed by Richard Crooks from the University of Texas can test for more substances in a smaller surface area, and provide results for more complex tests.
“This is about medicine for everybody,” said Crooks. “Anybody can fold them up. You don’t need a specialist, so you could easily imagine a NGO with some volunteers folding these things up and passing them out. They’re easy to produce, so the production could be shifted to the clientele as well. They don’t need to be made in the developed world.”
Crooks designed the sensor with doctoral student Hong Liu, who was inspired by a paper by chemist George Whiteside. He was the first to build a 3D microfluidic paper sensor that could test for biological targets – but his sensor was time-consuming to build and expensive.
“They had to pattern several pieces of paper using photolithography, cut them with lasers, and then tape them together with two-sided tape,” said Liu. “When I read the paper, I remembered when I was a child growing up in China and our teacher taught us origami. I realised it didn’t have to be so difficult. It can be very easy. Just fold the paper and then apply pressure.”
The sensor can be fabricated on a single sheet and folded into multiple layers in less than a minute with no tools or special techniques – just fingers!
The sensor works in the same way as a home pregnancy test. A hydrophobic material is laid down in tiny canyons on chromatography paper which channel the sample – blood, saliva or urine – regents embedded in the paper. When the sample hits the target, it reacts in a detectable way.
The pair has tested the sensor in glucose and a common protein, and has engineered a way to add a simple battery to their sensor so it can run tests that require power. Their results have been published in Analytical Chemistry.
