In remote regions of the world where electricity is hard to come by and scientific instruments are even scarcer, conducting medical tests at a doctor’s office or medical lab is rarely an option. Scientists are now reporting progress toward an inexpensive point-of-care, paper-based device to fill that void with no electronics required.

Conventional medical tests, conducted at a doctor’s office or clinical laboratory, detect or monitor disease with a hand-held or desktop electronic device. The team developed a new paper-based device that is about the size of a stick of gum. After applying a sample to the device, a small white dot turns green if the enzyme is present. After a few seconds or minutes, another small white dot turns green. The longer it takes for the second dot to change color after the first, the higher the concentration of the enzyme. The device uses just a few inexpensive materials and can be altered to measure a wide range of enzymes to monitor many different conditions.