Opto-microfluidic devices with femtosecond laser microfabrication

Zhang, Daiying (2016) Opto-microfluidic devices with femtosecond laser microfabrication. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Opto-microfluidics is a novel technology that integrates optical devices and systems with microchannels to investigate the properties of fluids. Opto-microfluidic devices have been increasingly recognized as important miniaturized devices for optical measurements, biological analyses, and chemical syntheses. These devices significantly reduce reagent consumption, waste production, analysis time and labour costs. Common fabrication techniques include soft lithography, microelectromechanical systems (MEMS) and hot embossing. In this dissertation, opto-microfluidic devices fabricated by two-photon polymerization (TPP) technique with femtosecond lasers and standard soft lithography are proposed. After analyzing the fabrication properties of the femtosecond laser, we choose optimal parameters to fabricate optical structures in photoresist material SU-8, and integrate them with microchannels which are produced by a standard soft lithographic technique. Diffractive grating, Mach-Zehnder interferometer (MZI) and optical microring resonators based refractive index (RI) and temperature sensors are designed, fabricated and demonstrated. The sensitivities in different conditions are thoroughly investigated. By combining fluid mechanics and optics, two functional opto-microfluidic devices realizing simultaneous particle sorting and RI sensing are successfully proved. In these devices, filters fabricated by femtosecond lasers are used to sieve and control the flow of particles in suspension, and then the purified liquid is induced into the optical structures to measure the RI. The opto-microfluidic devices described in this dissertation verify the practicability and effectiveness as a lab-on-a-chip platform.

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