Innovative microfluidic tools to support the emerging algal bio-oil farmer

Substantial private and public investment in algal biofuels is driving growth in the acreage dedicated to algae farming. Algal lipid production and accumulation follows a complex pattern driven by the daily light/dark cycle, ambient temperature, culture age, and nutrients. Algal ponds are also subject to “culture crash” caused by invasive species. At small scale, optimization of bio-oil productivity relies on monitoring at centralized analytical labs. The emerging large-scale algal farming industry requires distributed analytical tools that support optimized bio-oil production. This research is developing microeddy-based tools for performing cell titre, lipid production, and species identification on a low cost, compact platform. Our patented devices create microeddies that can be used for trapping single-cells in isolation or as arrayed elements. The heart of the microfabricated device relies on low cost PDMS/glass microchannels with an oscillating flow driven by low power piezoelectric pumps. A critical aspect of the design is identifying the device geometry that improves trapping stability at the lowest applied shear stress. We compare device performance with corresponding numerical simulations to provide detailed design guidelines. With proper design, these microeddies can trap both motile and non-motile algal cells and maintain viability for up to 6 days. Fluorescent assays are performed at the single cell level to acquire real-time single-cell data that can be aggregated into culture-based population statistics. We show that this device is well-suited for in-field sampling and analysis of algal ponds.