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

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.