Selective activation of redox-polymer-modified electrodes in a small volume in magnetic fields will be investigated to control microfluidics spatially and temporally. This new form of magnetohydrodynamics (MHD), as opposed to adding redox species to the solution or not adding them at all, defeats problems that hinder MHD from use in lab-on-a-chip (LOAC) devices. It allows higher currents with lower voltages, and thus, higher MHD forces and faster velocities without bubble formation or corrosion, faster response times, and compatibility with detectors and samples. MHD offers greater versatility over other micropumps, because flow can be programmed without redesigning channels of a device. An interdisciplinary, preexisting collaboration of investigators in Chemistry & Biochemistry at the Univ. of Arkansas and in Mechanical & Aerospace Engineering at Missouri Univ. of Science & Technology will perform the research.
Intellectual Merit : Reduction/oxidation of chemical species confined to polymer films on electrodes creates an ionic current in solution. When at right angles to the magnetic field, the resulting MHD force causes fluid to flow there in the third dimension. Individually-addressable electrodes will be fabricated in desired patterns, polymer films will be polymerized and characterized by electrochemistry, electrodes will be activated with current and voltage in magnetic fields, and flow will be monitored by microbead movement in solution. The objectives are to (1) establish large coulombic capacity, fast response, and equivalent circuit models for redox-polymer films on electrodes, (2) control and maximize flow velocities, tune profiles, switch direction, and drive adjacent counter-flows using concentric disk-ring configurations of redox-polymer-modified electrodes perpendicular to a magnetic field, (3) sustain fluid flow by recharging redox-polymer films, and (4) use simulations to obtain spatial maps of ionic current density, MHD force density, and fluid velocities as a function of time, compare with experiment, and evaluate parameters that exceed experimental limits to better design redox-MHD microfluidic devices.
Broader Impacts : The goal is to control microfluidics in a programmable way with far-reaching consequences toward products of interest to the public, such as hand-held, self-contained chemical analysis units for medical, environmental, and household uses. The interdisciplinary nature of the project enhances training of students involved in the research. Completed software modules will become available for testing and further evaluation to the scientific community free of charge. An outreach collaboration between science, math, and language arts teachers at The New School and mentors at the U of A and Missouri S&T will use MHD as a starting point to stimulate viral learning for middle school students on topics of forces and energy. Students will perform self-directed projects in collaboration with teachers and mentors, communicate results with videos using their own vocabulary and perspective, which they have scripted, edited, produced, and post them on the internet for public viewing and commentary. This approach is expected to bridge the gap between university research and middle school education, while simultaneously enhancing STEM education and educator development and increasing public scientific literacy and public engagement with science and technology.
