Edible silk lenses could spot germs

Liquid silk can be used to make edible nanoscale optical devices and sensor platforms that could be used to monitor food and health, US researchers say.

Silk cocoons are boiled in water to produce a purified silk solution that can be poured onto glass moulds to produce optical elements such as diffraction gratings and microlens arrays.

Critically the latter part of this process can be done at room temperature, allowing the embedding of chemical sensors that would be destroyed by heat, say the research team in the biomedical department at Tufts University.

The silk has no adverse effects on the body and is one of the strongest materials known.

Professor David Kaplan, head of the department, said the technology could be used to embed cheap sensors in bags of food to warn if they contain dangerous levels of bacteria. The sensors would be eaten with the food.

Another use would be an implantable device that could measure glucose levels in your blood for a year before dissolving.

Associate Professor Fiorenzo Omenetto said there is currently a lack of sophisticated optical devices that are both biodegradable and biocompatible. One exciting expect was that biosensors that would normally degrade survive when embedded in the silk, which can be formed into optical systems to facilitate the monitoring of their activity.

He told the Tufts newsletter: "It’s entirely a new thing. You sense that there’s a lot of potential in the air.”