Thermally-Triggered Effervescent Mixing for Assay Automation

Meltable barriers are an attractive means to achieve controlled delivery of reagents in a variety of settings, enabling assays to be performed through thermal automation instead of manual addition of reactants. However, mixing kinetics in such systems can be slow due to the lack of active flow or mechanical shaking. We demonstrate a new strategy for hands-free, thermally-automated agitation of biochemical reactions. Reagents for binary effervescent reactions are lyophilized then capped with a phase-change partition, eicosane. This barrier can be melted at moderate temperatures, at which point an aqueous solution dissolves the reactants, generating bubbles that mix the solution through convection. We explore reactions that generate bubbles of carbon dioxide and oxygen gasses, characterizing the induced mixing rate of two aqueous solutions with dissimilar densities. This strategy affords control over the initiation and duration of convective mixing, providing a tool for thermal automation of biochemical reactions with efficient reaction kinetics.