Integration of an Optical Ring Resonator Biosensor into a Self-Contained Microfluidic Cartridge with Active, Single-Shot Micropumps

While there have been huge advances in the field of biosensors during the last decade, their integration into a microfluidic environment avoiding external tubing and pumping is still neglected. Herein, we show a new microfluidic design that integrates multiple reservoirs for reagent storage and single-use electrochemical pumps for time-controlled delivery of the liquids. The cartridge has been tested and validated with a silicon nitride-based photonic biosensor incorporating multiple optical ring resonators as sensing elements and an immunoassay as a potential target application. Based on experimental results obtained with a demonstration model, subcomponents were designed and existing protocols were adapted. The newly-designed microfluidic cartridges and photonic sensors were separately characterized on a technical basis and performed well. Afterwards, the sensor was functionalized for a protein detection. The microfluidic cartridge was loaded with the necessary assay reagents. The integrated pumps were programmed to drive the single process steps of an immunoassay. The prototype worked selectively, but only with a low sensitivity. Further work must be carried out to optimize biofunctionalization of the optical ring resonators and to have a more suitable flow velocity progression to enhance the system’s reproducibility.The authors would like to thank the European Union for their funding of the project PBSA “Photonic Biosensor for Space Application” within the FP7-program (FP7 program Grant Agreement No. 312942-PBSA. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI

Femtosecond laser microfabrication of spiral optofluidic sensor and its sensing applications

Optofluidics combines the advantages of optics and microfluidics to achieve new functionalities. On account of cost-effectiveness, size-miniaturization, and structure-flexibility of optofluidic devices, there has been an increasing interest in optofluidics- related research since the emergence of the concept of optofluidics, such as lab-on-a-chip devices, optofluidic-based lenses and sensors, fluid-based particle sorters, optofluidic lasers, and imaging tools. In this thesis, femtosecond laser is explored to study the nonlinear interactions between ultrashort laser pulses and photoresist materials, and the possible applications in optofluidics. Based on the effect of two-photon absorption occurred in transparent photoresist materials, spiral-shaped waveguides of different specifications are fabricated with femtosecond laser in photoresist SU-8-2. Each of the waveguides, which contains one bus waveguide and one spiral-shaped waveguide with a distinct circumference, can be integrated into one microchannel on a glass substrate to form a spiral optofluidic device as an optofluidic sensor. The sensor with the highest sensitivity is utilized to measure physical properties of various fluidic samples (calcium chloride, cow milk and its related products, non-diary milk, and sucrose). These properties include temperature, refractive index, positive pressure and concentration. Experimental results indicate that the highest sensitivities for fluidic measurement are -0.47±0.02 nm/ᴼC for temperature sensing, 188.78±3.76 nm/RIU for refractive index sensing, 0.089±0.03 nm/ (N/m²) for positive pressure sensing, and 1.66±0.06 nm/wt% for concentration sensing. All devices have been fabricated with the use of small-sized low-cost materials and easy-to-replicate fabrication techniques. The effectiveness and applicability of the spiral optofluidic devices demonstrated in this thesis revealed the significance of nonlinear optical interactions between ultrashort light pulses and photosensitive materials, and their importance in many applications

Advances in Optofluidics

Optofluidics a niche research field that integrates optics with microfluidics. It started with elegant demonstrations of the passive interaction of light and liquid media such as liquid waveguides and liquid tunable lenses. Recently, the optofluidics continues the advance in liquid-based optical devices/systems. In addition, it has expanded rapidly into many other fields that involve lightwave (or photon) and liquid media. This Special Issue invites review articles (only review articles) that update the latest progress of the optofluidics in various aspects, such as new functional devices, new integrated systems, new fabrication techniques, new applications, etc. It covers, but is not limited to, topics such as micro-optics in liquid media, optofluidic sensors, integrated micro-optical systems, displays, optofluidics-on-fibers, optofluidic manipulation, energy and environmental applciations, and so on

Optofluidic Approaches for Enhanced Microsensor Performances

Optofluidics is a relatively young research field able to create a tight synergy between optics and micro/nano-fluidics. The high level of integration between fluidic and optical elements achievable by means of optofluidic approaches makes it possible to realize an innovative class of sensors, which have been demonstrated to have an improved sensitivity, adaptability and compactness. Many developments in this field have been made in the last years thanks to the availability of a new class of low cost materials and new technologies. This review describes the Italian state of art on optofluidic devices for sensing applications and offers a perspective for further future advances. We introduce the optofluidic concept and describe the advantages of merging photonic and fluidic elements, focusing on sensor developments for both environmental and biomedical monitoring