| Description | Dramatic nano-fluidics harnessed for active membrane systems
Abstract:
Carbon nanotubes (CNT) have three key attributes that make them of great interest for novel membrane applications: 1) atomically flat graphite surface allows for ideal fluid slip boundary conditions for 10,000 fold faster fluid flow, 2) the cutting process to open CNTs inherently places functional chemistry at CNT core entrance for gatekeeper activity, and 3) CNT are electrically conductive allowing for electrochemical reactions and application of electric fields gradients at CNT tips. Pressure driven flux of a variety of solvents (H2O, hexane, decane ethanol, methanol) are 4-5 orders of magnitude higher than conventional Newtonian flow due to atomically flat graphite planes inducing nearly ideal slip conditions. However this is eliminated with selective chemical functionalization needed to give chemical selectivity. These unique properties allow us to explore the hypothesis of producing ‘Gatekeeper’ membranes that mimic natural protein channels. With anionic tip functionality strong electroosmotic flow is induced by unimpeded cation flow with similar 10,000 fold enhancements. With enhanced power efficiency, carbon nanotube membranes were employed as the active element of a switchable transdermal drug delivery device that can facilitate more effective treatments of drug abuse and addiction. Mesoporous monoliths with biofunctional chemistry on electrodes at pore entrances have also shown active membrane pumping in cycles that mimic biological cell wall transporters. This membrane platform has also been coupled to photocatalysis of Au plasmons at pore entrances for controlled oxidation and demonstrated >300% quantum efficiency due to catalytic hot electron generation. Other major project area is the regeneration of dialysate in kidney dialysis that is a critical unmet need to enable portable/ambulatory dialysis treatments. This has been achieved using urea-selective osmotic membranes and highly crystalline TiO2 nanowires with high conductivity to collector electrode to separate electron-hole pairs and decompose urea to safe N2 and CO2 products. Applications of active membrane ranging from drug delivery, pharmaceutical production, kidney dialysis, catalysis and water remediation are highlighted.
Bio:
Professor Hinds has a formal and research-based background in chemistry and electronic device processing. He has a BS in Chemistry from Harvey Mudd College and his Ph.D. work (1996) was on the MOCVD growth of high temperature superconductors at Northwestern University. Post-doctoral work at NC State Physics to study the interface states in the Si/SiO2 system. He then received an NSF-JSPS fellowship to work with nano-scale fabrication of single electron floating gate memory at the Tokyo Institute of Technology. He joined the Chem. & Mater. Engr faculty at Univ. of Ky in 2001. The focus of his research group is trying to produce nano-scale materials that can mimic natural process for applications ranging from health care, energy storage/generation and water purification. In 2014 he moved to University of Washington MSE department. He has received a Presidential Early Career Award (PECASE) award sponsored by NIH, Kavli frontiers fellow and Campbell Professor of Materials Science & Engineering. |
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