Selective optical sensing of glucose based on ordered nanowires/disordered porous Si hybrid structure

摘要

Recently, bio/chemical sensors are widely used in the fields of medical diagnostics, environmental monitoring, and food safety. Among them, reflection interference spectroscopy sensor has significant advantages in real-time, label-free and non-destructive detection. However, reflective interferometer sensors are mainly based on porous materials with a small variation range of the aperture size, and flow of the measured molecules is not smooth in the semi-closed nanopores, leading to the limited detection range, long response time and poor anti-interference ability. In this work, we experimentally demonstrate a real-time reflective interferometric optical sensing system based on the ordered nanowires/disordered porous Si hybrid structure. Combined with an optical fiber spectrometer and a microfluidic unit, our constructed sensor can realize the selective detection of glucose molecules. The peak shift of fast Fourier transform (FFT) spectrum can be up to 308.6 nm as the glucose concentration changes at 1 mol/L. The response time is about 80 s, and the linear range is from 2 mmol/L to 3 mol/L. The proposed hybrid structure is much superior in sensitivity and response time as compared to the sensors based on the double-layer porous Si, and can simultaneously realize the selective detection of both large and small molecules under reasonable design, while the sensors based on single layer of order Si nanowires or porous Si cannot. This work opens a pathway for label-free and selective sensing in the circumstances of mixed large and small molecules, which expands the functions and applications of reflective interference optical sensors.