COMPACT OPTOFLUIDIC REFRACTOMETER BASED ON PHASE TRANSMISSION GRATING

In this paper, a compact optofluidic refractometer is demonstrated. Consisting of a transmitting grating structure with rectangular grooves integrated into a microfluidic network, its working principle is based on the effect of the refractive index of a sample fluid that fills the groove space on the zeroth-order diffraction intensity. The performance of the device is dependent on grating structure parameters such as thickness. Theoretical analysis and experimental measurements agree well with each other and both demonstrate that a thicker grating results in higher sensitivity but a smaller measurement range, and vice-versa. It can also be expected that smaller changes in refractive index can be resolved by using a detector with a lower detection limit.