Optofluidic refractometer using resonant optical tunneling effect

Abstract

This paper presents the design and analysis of a liquid refractive index sensor that utilizes a unique physical mechanism of resonant optical tunneling effect ͑ROTE͒. The sensor consists of two hemicylindrical prisms, two air gaps, and a microfluidic channel. All parts can be microfabricated using an optical resin NOA81. Theoretical study shows that this ROTE sensor has extremely sharp transmission peak and achieves a sensitivity of 760 nm/refractive index unit ͑RIU͒ and a detectivity of 85 000 RIU −1 . Although the sensitivity is smaller than that of a typical surface plasmon resonance ͑SPR͒ sensor ͑3200 nm/RIU͒ and is comparable to a 95% reflectivity Fabry-Pérot ͑FP͒ etalon ͑440 nm/RIU͒, the detectivity is 17 000 times larger than that of the SPR sensor and 85 times larger than that of the FP etalon. Such ROTE sensor could potentially achieve an ultrahigh sensitivity of 10 −9 RIU, two orders higher than the best results of current methods.

Resonant optical tunneling-induced enhancement of the photonic spin Hall effect

“…The calculation results show that maximum transverse shifts of ppolarized light of 22.25 µm can be achieved without any amplification method. This suggests it is possible to use the ROTE to explore the appli cation of optical switches [33,34], refractive index sensors [35][36][37] and determine the thickness of nanometal films [38].…”

A microfluidics assisted porous silicon array for optical label-free biochemical sensing

“…In the present work, we describe the integration of a PSi microarray made of Bragg mirrors with a microfluidic circuit made of polydimethylsiloxane (PDMS): the combination of optics and microfluidics can boost technology towards new devices for biosensing. [15][16][17] The integration of a PSi transducer in an optical microsystem is never straightforward nor trivial from the technology point of view: 18,19 the applied microfluidic system, which strongly reduces the functionalization time, chemicals and biological products consumption, should also preserve all the features of the PSi label-free optical detection. On the other side, the integration of such optical transducers in a microsystem is an unavoidable step towards the realization of an industrial prototype, which could be considered for production purposes.…”

Optofluidics Refractometers

“…Thus, to accurately describe sensor performance, a comprehensive evaluation that includes sensitivity and quality factors is crucial. Several novel parameters, such as figure of merit (FOM) [ 51 ] or detectivity [ 52 ], have been proposed in some papers. FOM is defined as the ratio of sensitivity to full wave at half maximum (FWHM) as Equation (1), which can take both of the sensitivity and Q value into consideration, thus the performance of the sensor can be characterized accurately by using a single parameter.…”