Biofilm oxygen profiling using an array of microelectrodes on a microfabricated needle

Abstract

Knowledge of bacterial activity inside biofilms is key to the optimization of applied biotechnologies. A novel dissolved oxygen microelectrode array (DO-MEA) sensor has been designed and fabricated on a needle using microelectromechanical systems technology, in order to provide a multipoint, simultaneous dissolved oxygen snapshot profile inside a biofilm. The sensor consisted of eleven gold disk electrodes with integrated counter (CE) and pseudo-reference (RE) electrodes. Three different sensor designs are fabricated, and their responses are fully characterized and evaluated under different environmental conditions. The developed sensor is validated against a commercial Clark-type microelectrode overcoming its drawbacks, by profiling a heterotrophic biofilm cultivated in a flat-plate bioreactor. The DO-MEA sensor will be improved with the protection of the electrodes and will be fabricated on a thinner substrate, for becoming a powerful tool for the research of many similar biological-based processes and applications.