Three Dimensional Paper Sensor Could Test for Disease

Sensors can be printed out on an office printer, and take less than a minute to assemble.

These low-cost, "point-of-care" sensors could be useful in the developing world, where resources are often lacking to pay for lab-based tests, and where, even if the money is available, there infrastructure does not exist to transport biological samples to the lab.

Inspired by the paper-folding art of origami, chemists at The University of Texas at Austin (Texas; USA) have developed a 3-D paper sensor that may be able to test for diseases such as malaria and HIV.

One-dimensional paper sensors, such as those used in pregnancy tests, are already common but have limitations. The folded, 3-D sensors, developed by Richard Crooks, the Robert A. Welch professor of chemistry and doctoral student Hong Liu, can test for more substances in a smaller surface area and provide results for more complex tests.

"Anybody can fold them up," said Prof. Crooks. "You don't need a specialist, so you could easily imagine an [non-governmental organization] NGO with some volunteers folding these things up and passing them out. They're easy to produce as well, so the production could be shifted to the clientele as well. They don't need to be made in the developed world."

Prof. Crooks said that the principles underlying the sensor, which have been successfully tested on glucose and a common protein, are related to the home pregnancy test. A hydrophobic material, such as wax or photo resist, is laid down into tiny canyons on chromatography paper. It channels the sample to be tested—urine, blood, or saliva, for instance—to spots on the paper where test reagents have been embedded.

If the sample has whatever targets the sensor is designed to detect, it will react in an easily detectable manner. It might turn a specific color for example or fluoresce under a UV light. Then it can be read by eye.

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