A multiplexing fiber optic microsensor system for monitoring spatially resolved oxygen patterns

Single channel luminescent oxygen-quenched optrodes and micro optrodes have been commercially available for over a decade. However, many field experiments in biological research require multiple oxygen sensors to collect large spatial datasets, or to monitor real time oxygen transport in various regions of interest. This paper demonstrates the design, validation, and application of a fiber optic oxygen microsensor system that is designed to conduct real-time measurements of multiple samples in field studies. The ten channel system was validated in laboratory conditions and then used to monitor spatially resolved, real time oxygen concentration in marine microbial mats, agricultural soil, and developing seeds. Sensor stability, drift, sensitivity, and response time were similar to a single channel commercial technology. The effects of temperature and salinity were analyzed and compared to a commercial micro optrode system (there was no statistical difference in performance between the two systems). In addition to the multiplexing capability, an advantage of the system developed here is the ability to map oxygen gradients in three dimensions. The multiplexing system is a minimally invasive tool for in vivo monitoring of form-function relationships with sub-millimeter spatial resolution.