Chemists at The University of Texas at Austin have developed a 3-D paper sensor that may be able to test for diseases such as malaria and HIV for less than 10 cents a pop. Such low-cost, ‘point-of-care’ sensors could be incredibly useful in the developing world, where the resources often don’t exist to pay for lab-based tests. The principles underlying the sensor, which have beens uccessfully tested on glucose and a common protein, 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’ll react in an easily detectable manner. It might turn a specific color, for instance, or fluoresce under a UV light.