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.