We design, model and build tools that solve complex biochemical and environmental chemical puzzles. Most of this involves microfluidics, a field that builds the chemical analogues to integrated circuit chips. For example, we have built “lab-on-a-chip” devices to detect antimalarial drug adulteration, measure disease biomarkers in biological fluids, synthesize genes and detect toxins in the environment. These applications all require innovations in design, materials, and fabrication, yet build on longstanding chemical principles routinely applied in separations, surface chemistry and fluid dynamics.