Microbially-mediated redox cycling of oxygen, iron, manganese, and sulfur exerts a strong influence on the behavior of various organic and inorganic compounds in the deep subsurface biosphere and has been relevant to the co-evolution of the earth and life through geologic time scales; sensors that enable improved understanding and characterization of processes involving such redox-reactive chemical species are of key relevance to the C-DEBI mission. The work proposed is to attempt new methods of solid-state voltammetric microelectrode fabrication to enable new sensor configurations and environmentally-relevant experiments. We aim to: (i) make in vitro working electrodes smaller than previously available for increasing spatial resolution with respect to characterizing single-to-several cell scale processes in laboratory experiments, and (ii) make in situ working electrodes effectively larger than previously available for increasing sensitivity and thus lowering detection limits for characterization of redox reactive chemical species in field studies. Successes in each objective will significantly enhance upcoming lab and field work at Juan de Fuca Ridge CORKs and North Pond.
