One foundational motivation for chemical sensing is that knowledge of the presence and level of a chemical agent informs decisions about treatment of the agent, for example by sequestration, separation or chemical conversion to a less harmful substance. Commonly the sensing and treatment steps are separate. However, the disjoint detection/treatment approach is neither optimal, nor required. Thus, we are investigating how nanostructured architectures can be constructed so that molecular transport (analyte/reagent delivery), chemical sensing (optical or electrochemical) and subsequent treatment can all be coupled in the same physical space during the same translocation event. Chemical sensors that are uniquely well-poised for integration into 3-D micro-/nanofluidic architectures include those based on plasmonics and impedance. Following detection, treatment can be substantially enhanced if mass transport limitations can be overcome. In this context, in situ generation of reactive species within confined geometries, such as nanopores or nanochannels, is of significant interest, because of its potential utility in overcoming mass transport limitations in chemical reactivity. Solvent electrolysis in electrochemically coupled nanochannels supporting electrokinetic flow for the generation of reactive species, can produce arbitrarily tunable quantities of reagents, such as O₂ or H₂, in situ in close proximity to the site of a hydrogenation catalyst, for example. Semi-quantitative estimates of the local H₂ concentration are obtained by comparing the spatiotemporal fluorescence behavior and current measurements with finite element simulations accounting for electrolysis and subsequent convection and diffusion within the confined geometry. H₂ saturation can easily be achieved at modest overpotentials.

Date Published: 22 May 2014
PDF: 11 pages
Proc. SPIE 9107, Smart Biomedical and Physiological Sensor Technology XI, 91070L (22 May 2014); doi: 10.1117/12.2048522

Published in SPIE Proceedings Vol. 9107:
Smart Biomedical and Physiological Sensor Technology XI
Brian M. Cullum; Eric S. McLamore, Editor(s)