Spider silk has light guiding properties that have been used to create a sensor that can detect changes in the refractive index of biological solutions including glucose.

The spider silk sensor was developed by a team at the National Yang Ming Chiao Tung University in Taiwan and it is their hope that it could be used to measure blood sugar levels.

Spider silk is suitable for this application due to its ability to transmit light similarly to optical fibres while also being elastic and very strong. The researchers used silk from a species of golden orb-web spider.

The optical fibre structure is 100 microns (0.1 mm) in diameter, consisting of a spider silk core and resin cladding. A biocompatible nanolayer of gold is added to enhance the sensitivity of the sensor.

The research conducted showed that the spider silk sensor can determine exact concentration levels of fructose, sucrose and glucose all based on the refractive index of the solution.

The research team leader Cheng-Yang Liu said, “Glucose sensors are crucial to people with diabetes, but these devices tend to be invasive, uncomfortable and not cost-efficient. With spider silk attracting attention for its superior optomechanical properties, we wanted to explore using this biocompatible material to optically detect various sugar concentrations in real-time.”

For the spider silk fibre to take measurements on end is placed in the liquid sample solution and the other end is connected to a light source and spectrometer. The researchers compared the results to readings from a commercial refractometer and the spider silk was able to correctly identify the type of sugar and concertation levels.

More tests are required to improve the sensors accuracy under changing environmental conditions before it can be used for real time measurements.