An ultra-low detection-limit optofluidic biosensor based on all glass Fabry-Perot cavity

An all glass optofludic biosensor with high quality-factor Fabry-Perot cavity (FPC) channel was reported. The all glass sandwich structure can completely eliminate the etching roughness of the channel surface, and can extend the operating wavelength to visible and ultraviolet regions compared with that of Si-based sensor. The quality-factor of the FPC channel is 875, and the system noise can be reduced to 1.2 nV by combining optical differential detection with phase lock-in detection. A detection limit of 15ng/mL for glucose solution, which corresponds to a refractive index unit of 2.0 × 10^-9, was experimentally demonstrated. The all glass FPC sensor features low cost and robust compared with surface-plasmon-resonance sensor and ring-resonator sensor.