Patterned paper is a game-changing technology for delivering low-cost medical care in the developing world. Paper is inexpensive, universally available, and compatible with many biological and chemical assays. To fabricate a diagnostic device, DFA patterns channels and assay zones (or wells) of water-repellant materials into a piece of paper roughly the size of a postage stamp. Biological and chemical assay reagents are then deposited in the wells. When blood, urine, saliva, sweat or other biological samples are applied to the device, the paper wicks the sample through the channels to the assay zones, without external pumps or power. Upon contact, the assay zone quickly changes color and results are then easily read by comparing the color change with a reference scale printed on the device. After use, the device can be easily disposed of by burning. As we develop more advanced diagnostics, DFA’s paper devices can be embedded with electrical circuitry to enable resistive heating, electrochemical assays, or initial processing of assay results.
