U-shaped fiber-optic ATR sensor enhanced by silver nanoparticles for continuous glucose monitoring

•Five glucose absorption wavelengths were emplyed for specific glucose detection to overcome the drawbacks of enzyme electrodes based glucose sensor.•Silver nanoparticles were prepared on the U-shaped fiberATR sensor to enhance the glucose sensing for implantable continuous glucose monitoring.•Fabrication of silver nanoparticles on cylindrical surface of fiber ATR sensor by chemical reduction of its silver halide materials directly was proposed.

An implantable U-shaped fiber ATR sensor enhanced by silver nanoparticles on cylindrical surface was presented for continuous glucose monitoring to overcome the drawbacks of traditional glucose sensing technique based on enzyme electrodes. A U-shaped structure was addressed to increase effective optical length at limited implantable space to enhance the sensitivity of fiber ATR sensor. A novel method to fabricate silver nanoparticles on cylindrical surface of U-shaped fiber ATR sensor based on chemical reduction of its silver halide material directly without any preliminary nanoparticles synthesis and following covalent bond or self-assembly was proposed. Five glucose absorption wavelengths in the mid-infrared band were employed for specific glucose monitoring. The experimental results indicate that the sensitivity and resolution of the silver-nanoparticle-enhanced U-shaped fiber-optic ATR sensor are approximately three times those of a conventional one. The high sensitivity and low-noise performance makes it promising for in vivo glucose monitoring in the future clinical applications.