Researchers create biosensor by turning spider silk into optical fiber: New sensor can measure unknown sugar concentrations in real-time

Researchers have harnessed the light-guiding properties of spider silk to develop a sensor that can detect and measure small changes in the refractive index of a biological solution, including glucose and other types of sugar solutions. The new light-based sensor might one day be useful for measuring blood sugar and other biochemical analytes.

“Glucose sensors are crucial to people with diabetes, but these devices tend to be invasive, uncomfortable and not cost-efficient,” said research team leader Cheng-Yang Liu from National Yang Ming Chiao Tung University in Taiwan. “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.”

Liu and colleagues from Taiwan Instrument Research Institute and Taipei Medical University describe their new sensor in the Optica Publishing Group journal Biomedical Optics Express. They show that it can be used to determine concentrations of fructose, sucrose and glucose sugars based on changes in a solution’s refractive index. Spider silk is ideal for this application because it can not only transmit light like an optical fiber but is also very strong and elastic.

“Our new spider silk-based fiber optic sugar sensor is practical, compact, biocompatible, cost-effective and highly sensitive,” said Liu. “With further development, it could lead to better at-home medical monitoring devices and point-of-care diagnostic and testing devices.”

From silk to sensor

To make the sensor, the researchers harvested dragline spider silk from the giant wood spider Nephila pilipes, which is native to Taiwan. They enveloped the silk, which is just 10 microns in diameter, with a biocompatible photocurable resin and cured it to form a smooth protective surface. This created an optical fiber structure that was 100 microns in diameter, with the spider silk acting as the core and the resin as the cladding. They then added a biocompatible nano-layer of gold to enhance the fiber’s sensing abilities.

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