Color-Changing Ink

A silk-based ink that changes color when exposed to certain chemicals could be used to create a whole new generation of “wearables” for health and environmental monitoring.

The first step was to create inks that respond predictably to various reactive substances. Silk was used as a base because of its ability to protect the compounds and prevent them from losing function when added to the ink. Sodium alginate was then added to thicken the mix and make it suitable for screen printing. When printed on a fabric garment, the reactive molecules can be used to indicate a variety of factors. For example, pH sensitive compounds could provide a measure of dehydration, while lactate oxidase indicators could measure fatigue. The compounds can also be adapted to react to bacteria or to track dangerous gases in the environment.

Further studies will focus on quantifying color changes to provide clinically actionable information based on ambient lighting conditions and the types of cameras used. Regardless, the new technology has the potential to revolutionize wearable sensors by replacing today’s rigid and bulky designs.