Tactile alternative to colour changes

Many instrument-free analytical methods, such as pH test strips and home pregnancy tests, indicate their results with a colour change. Now scientists in the US have devised a system that outputs a signal you can feel as well as see.

The tactile system, devised by Tatiana Fedotova and Dmitry Kolpashchikov at the University of Central Florida, is based on the radical-mediated polymerisation of acrylamide into polyacrylamide. A gel, as opposed to a liquid, indicates a positive result.

As a proof-of-concept, the team demonstrated that the system could detect ATP and two different DNA sequences. The researchers envision their technology could make home tests for a variety of biological analytes accessible to people who are visually impaired.