Solutal and thermal buoyancy effects in self-powered phosphatase micropumps.Immobilized enzymes generate net fluid flow when exposed to specific reagents in solution.  To uncover the mechanism of pumping, we examine the effects of solutal and thermal buoyancy on the behavior of phosphatase-based micropumps, using a series of reactants with known thermodynamic and kinetic parameters.  By combining modeling and experiments, we perform the first quantitative comparison of thermal and solutal effects in an enzyme micropump system.  Despite the significant exothermicity of the catalyzed reactions, we find that thermal effects play a minimal role in the observed fluid flow. 
THERM