Origami-Inspired Paper Sensor Offers Diagnostic Capabilities
Inspired by the paper-folding art of origami, scientists at The University of Texas at Austin have developed a 3D paper sensor that may be able to test for diseases such as malaria and HIV for less than 10 cents a pop. One-dimensional paper sensors, such as those used in pregnancy tests, are already common, but have limitations. The folded, 3D sensors, developed by Richard Crooks, a professor of chemistry, and Hong Liu, a doctoral student, can test for more substances in a smaller surface area and provide results for more complex tests. They are also easy to produce, so the production doesn't need to be limited to the developed world, researchers said.
Within a few weeks of experiments, Liu had fabricated the sensor on one simple sheet using photolithography or a simply an office printer in the lab. Folding it over into multiple layers takes less than a minute and requires no tools or special alignment techniques — just fingers. The principles underlying the sensor are related to the home pregnancy test. A hydrophobic material, such as wax or photoresist, is laid down into tiny canyons on chromatography paper. It channels the sample that's being 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 instance, or fluoresce under a UV light. Then it can be read by eye.
These low-cost, “point-of-care” sensors could be extremely useful in the developing world, where the infrastructure doesn't exist to transport biological samples to the lab. The researchers have also engineered a way to add a simple battery to their sensor so that it can run tests that require power. Their prototype uses aluminum foil and looks for glucose in urine. Crooks estimates that including such a battery would add only a few cents to the cost of producing the sensor.