Rapid Fabrication of Chip‐Based Physiometers for Neurobehavioral Toxicity Assays Using Rotifers Brachionus calyciflorus

Abstract

An increased interest in implementations of Lab-on-a-Chip (LOC) technologies for in-situ analysis of multicellular metazoan model organisms and their embryonic stages demands development of new prototyping techniques. Due to size of multicellular organisms the fabrication of soft-lithography molds requires features with high aspect ratios as well as deposition of layers with significant thicknesses. This makes them time consuming and difficult to fabricate using conventional photolithography techniques. In this work we describe development of a rapid technique capable of generating thick films achieved with high viscosity SU-8 and used in fabricating master templates for high aspect ratio micro- and mesofluidic devices. The cost effective and rapid method eliminated the need for multiple spin coating cycles as well as edge bead artifacts while preserving low surface roughness and superior surface uniformity. Due to elimination of spin coating steps, typically constrained to clean room facilities, the new method allows to significantly reduce microfabrication costs. We have utilized the prototyping technique to develop proof-of-concept chip-based devices capable of effectively caging freshwater rotifers Brachionus calyciflorus for high-definition video-microscopy analysis. The combination of time-resolved video-microscopy and chip-based physiometers enabled us to demonstrate new applications for neurobehavioral assays utilizing non-invasive sub-lethal end-points.

A rapid-prototyped moulding system towards optimised scalable fabrication of elastomeric microfluidic devices

“…The most common photoresist used for microfluidics soft lithography is SU-8, a liquid epoxy-based UV-cured resin, which is typically spin-coated onto a silicon wafer to attain an even layer. SU-8 may also be dispensed via constant-volume injection and allowed to self-level 23 , or manually spread with guide walls for higher-viscosity formulations to obtain layer thicknesses of up to 1500 um 24 . However, the process of spin-coating is inherently wasteful, which led to the development of photoresist films such as SUEX, ADEX or custom thick sheet dry films (TDFS) that are laminated onto the substrate.…”