Gradient-temperature hot-embossing for dense micropillar array fabrication on thick cyclo-olefin polymeric plates: An example of a microfluidic chromatography column fabrication

Scalable Processing of Cyclic Olefin Copolymer (COC) Microfluidic Biochips

Microfluidics evolved with the appearance of polydimethylsiloxane (PDMS), an elastomer with a short processing time and the possibility for replication on a micrometric scale. Despite the many advantages of PDMS, there are well-known drawbacks, such as the hydrophobic surface, the absorption of small molecules, the low stiffness, relatively high cost, and the difficulty of scaling up the fabrication process for industrial production, creating a need for alternative materials. One option is the use of stiffer thermoplastics, such as the cyclic olefin copolymer (COC), which can be mass produced, have lower cost and possess excellent properties. In this work, a method to fabricate COC microfluidic structures was developed. The work was divided into process optimization and evaluation of material properties for application in microfluidics. In the processing step, moulding, sealing, and liquid handling aspects were developed and optimized. The resulting COC devices were evaluated from the point of view of molecular diffusion, burst pressure, temperature resistance, and susceptibility to surface treatments and these results were compared to PDMS devices. Lastly, a target DNA hybridization assay was performed showing the potential of the COC-based microfluidic device to be used in biosensing and Lab-on-a-Chip applications.

Polymeric and Paper-Based Lab-on-a-Chip Devices in Food Safety: A Review

Food quality and safety are important to protect consumers from foodborne illnesses. Currently, laboratory scale analysis, which takes several days to complete, is the main way to ensure the absence of pathogenic microorganisms in a wide range of food products. However, new methods such as PCR, ELISA, or even accelerated plate culture tests have been proposed for the rapid detection of pathogens. Lab-on-chip (LOC) devices and microfluidics are miniaturized devices that can enable faster, easier, and at the point of interest analysis. Nowadays, methods such as PCR are often coupled with microfluidics, providing new LOC devices that can replace or complement the standard methods by offering highly sensitive, fast, and on-site analysis. This review's objective is to present an overview of recent advances in LOCs used for the identification of the most prevalent foodborne and waterborne pathogens that put consumer health at risk. In particular, the paper is organized as follows: first, we discuss the main fabrication methods of microfluidics as well as the most popular materials used, and then we present recent literature examples for LOCs used for the detection of pathogenic bacteria found in water and other food samples. In the final section, we summarize our findings and also provide our point of view on the challenges and opportunities in the field.

Potential of CO2-laser processing of quartz for fast prototyping of microfluidic reactors and templates for 3D cell assembly over large scale

Carbon dioxide (CO2)-laser processing of glasses is a versatile maskless writing technique to engrave micro-structures with flexible control on shape and size. In this study, we present the fabrication of hundreds of microns quartz micro-channels and micro-holes by pulsed CO2-laser ablation with a focus on the great potential of the technique in microfluidics and biomedical applications. After discussing the impact of the laser processing parameters on the design process, we illustrate specific applications. First, we demonstrate the use of a serpentine microfluidic reactor prepared by combining CO2-laser ablation and post-ablation wet etching to remove surface features stemming from laser-texturing that are undesirable for channel sealing. Then, cyclic olefin copolymer micro-pillars are fabricated using laser-processed micro-holes as molds with high detail replication. The hundreds of microns conical and square pyramidal shaped pillars are used as templates to drive 3D cell assembly. Human Umbilical Vein Endothelial Cells are found to assemble in a compact and wrapping way around the micro-pillars forming a tight junction network. These applications are interesting for both Lab-on-a-Chip and Organ-on-a-Chip devices.