Conference Agenda

Ultrafast laser micromachining is a technological innovation with exciting potential for many applications and has led to impressive advances in the study of light-matter interactions. In this context, the laser-assisted wet etching fabrication technique has opened new frontiers in the optofluidic lab-on-a-chip, i.e. complex and easy-to-use microsystems capable of integrating multiple physicochemical processes on a single platform to replicate specific chemical, biological and medical tests typically performed in a laboratory. These miniaturised multifunctional laboratories exploit the synergy between the high sensitivity of optics and the unique ability to manipulate small quantities of microfluidics to develop a new frontier of analytical devices. The chips can be manufactured in monolithic 3D versions with no geometric constraints and are fully embedded in the substrate (typically fused silica). In addition to the advantage of using an inert substrate (strategic for biological applications), the elimination of the sealing step and the high mechanical strength offer numerous advantages. To demonstrate the potential of this new sensing platform, we report on the benefits of integrating in-plane 3D micro-optics to increase the S/N in-chip spectroscopic analysis in two case studies: flow cytometer devices and innovative chips for real-time Raman analysis of bio-samples in flow, even non-transparent ones.

Optothermal manipulation of small objects ranging in size from micrometers down to nanometers has demonstrated a high degree of control over particle motion through a combination of optical and thermal forces. Here, we show that long-range optofluidic flows can be induced via the absorption of light on plasmonic nanostructures creating localized hot spots. Through temporal and spatial light modulation, we can precisely engineer fluid flows by controlling the thermal landscape. We combine in-situ measurements of induced thermal fields using optical diffraction tomography (ODT) with 3D optical tracking of particles via off-axis digital holographic microscopy (DHM) allowing us to precisely monitor light induced environmental changes. With the help of simulations, we analyze the individual contributions stemming from the thermal and optical forces. This comprehensive toolbox allows us to design specific fluid patterns in 3D creating optofluidic boundaries and obstacles that steer particle motion. Alternating between different patterns of illumination over time creates various types of microfluidic actuators such as pumps, traps, and valves, all within a single chip environment. Our optofluidic approach provides an alternative pathway to develop multifunctional microfluidic chips for integrated sorting, detection, and analysis.

Motivated by the need for improved platforms in biomedical research, this study addresses challenges associated with traditional Ussing chamber systems, widely used in studying biological barriers like the epithelial barrier of the gut. These challenges include complexity, high sample volumes, and limited compatibility. By combining stereolithography and soft lithography techniques, a microfluidic Ussing chamber is manufactured, overcoming these limitations, and incorporating compatibility with microscopy. Validation through Trans-Epithelial Electrical Resistance (TEER) measurements confirms its efficacy in assessing ion permeability dynamics, utilizing Caco-2 cell monolayers. The study showcases the capability of the manufactured chamber for sensing impact of calcium on tight junctions.

Agriculture challenges to reduce its environmental impact and to improve control over agricultural crops of agriculture are numerous. We develop here an optical integrated probe as potential answer to some detection challenges, based on a RIB chalcogenide waveguide. Early results have shown that the fabrication process induces sidewall roughness potentially altering the sensitivity of the probe. The numerical tool used here implements an approximation allowing to take into account sidewall roughness on propagation losses. This code is based on finite element method. Results show that sidewall roughness have a higher impact on losses for narrow waveguides.