To develop an operational microfluidic-based sensing system, the microfluidic technology needs to be integrated with, e.g., electrical or optical devices, that are required for interrogating of the obtained outcomes. Although the microfluidic systems themselves are usually highly miniaturized, most of them still require support of external, bulky systems, such as e.g., a fluorescent microscope . Therefore, a step ahead is to develop miniature interrogation subsystems, but still highly functional and compatible with microfluidics. To improve the sensing efficiency and tackle such challenges as portability and miniaturization of the whole system, optofluidic devices have been proposed where microfluidic (or nanofluidic) systems are integrated with optical sensing devices . Such solutions provide conditions for direct interaction between the examined fluid and light, what is expected e.g., in the field of biochemical sensing . Up to date a great variety of planar optical sensing solutions have been combined with microfluidics . Nevertheless, the sensitivity of such systems to changes in optical properties of the fluids, such as their refractive index (RI), is often relatively low, i.e., when a spectral shift of a pattern is concerned, it reaches a level of tens up to hundreds of nm per RI unit (RIU). Due to the low sensitivity, such an optical device may not be effective in biochemical applications and detection of biological targets. On top of sensitivity, a crucial issue is a proper integration and alignment of the optical components with microfluidic devices.