Continuous nondestructive monitoring of microbial biofilms: A review of analytical techniques

A fundamental requirement for the understanding and control of biofilms is the continuous nondestructive monitoring of biofilm processes. This paper reviews research analytical techniques that monitor biofilm processes in a continuous nondestructive manner and that could also be modified for industrial applications. To be considered 'continuous' and 'nondestructive' for the purpose of this review a technique must: (a) function in an aqueous system; (b)not require sample removal; (c) minimize signal from organisms or contaminants in the bulk phase; and (d) provide real-time data. Various microscopic, spectrochemical, electrochemical, and piezoelectrical analysis methods fulfill these criteria. These techniques monitor the formation of biofilms, the physiology of the microorganisms withiin biofilms, and/or the interaction of the biofilms with their environment. It is hoped that this review will stimulate development and use of biofilm monitoring techniques in industrial and environmental settings.