Optofluidic Devices and Platforms for Sensing Applications

Optofluidics is an emerging research field that combines the advantages of microfluidics and optics on the same platform towards highly functional and compact devices. This approach offers innovative design in order to increase performances and optical functionalities of sensing devices. In particular, the possibility to use a fluid as an optical material and guiding light through it offers very interesting solutions enabling unprecedented sensitivity and limit-ofdetection. In this work we present the design, fabrication and characterizations of optofluidics devices and microsystems for sensing applications that ranges from biosensing to environmental monitoring. The confinement properties and the strong light matter interaction between light and fluids occurring in optofluidics waveguides, like Antiresonant Reflecting Optical Waveguide (ARROW) or liquid jet waveguide, have been exploited to realize simple but effective and sensitive microfluidic sensors. The use of optofluidic waveguides for spectroscopy methods like absorption, fluorescence, Raman is illustrated showing that the optofluidic approach permits to overcome the sensitivity problems related to the reduced the interaction length of light with fluid due to device miniaturization. Besides the use of the waveguides itself as optofluidic sensor, we show that more sophisticated devices can be realized by using liquid core ARROWs. In particular, we demonstrate that single mode ARROWs provide the opportunity to implement sensor devices which make uses of interferometric phenomena that are very attractive for sensing applications as they combine high sensitivity with compactness and low-production cost. We show that, despite ARROWs are leaky waveguides high performance liquid core Mach-Zehnder interferometers (MZI) and Ring resonator could be realized. Finally we demonstrate the possibility to combine solid core with liquid core ARROWs and microfluidic devices in a single sensing platform. This represents a significant step towards an effective realization of chip scale integrated system. The integration of planar optofluidic components with microfluidic tools at the chip scale represents the future trend of sensing systems for point-of care diagnosis or in situ monitoring. Increasing the synergy between these technologies can lead to highly reliable and portable systems