A compact optofluidic refractometer is demonstrated. Consisting of a grating structure with rectangular grooves integrated into a microfluidic network, its working principle is based on the modulation of the zeroth-order diffraction intensity of the transmission induced by the refractive index (RI) of a sample fluid that fills the groove space. The performance of the device is dependent on the grating structure parameters such as thickness. Theoretical analysis and experimental measurements agree well with each other and both demonstrate that having a thicker grating results in higher sensitivity but a smaller measurement range, and vice versa. It can also be expected that smaller changes in the RI can be resolved by using a detector with a lower detection limit.
© 2009 Optical Society of America
Original Manuscript: March 13, 2009
Revised Manuscript: April 28, 2009
Manuscript Accepted: April 29, 2009
Published: June 2, 2009
Vol. 4, Iss. 8 Virtual Journal for Biomedical Optics
Hongbin Yu, Guangya Zhou, Fook Siong Chau, and Feiwen Lee, "Phase-transmission-grating-based compact optofluidic refractometer," Opt. Lett. 34, 1753-1755 (2009)