Quartz tuning fork as in situ sensor of bacterial biofilm

Abstract

Piezoelectric quartz tuning forks (QTFs) were used as in situ sensors of biofilm formation. Modulated excitation technique allowed to measure the current generated by the QTF during the ring-down of the oscillations at conductive environments such as a liquid culture growth medium. New algorithm of the digital analysis of the ring-down signal was elaborated and used to determine the decay time constant of the vibrations and the damped vibration frequency. The dependence of these parameters on the time for QTF placed in liquid growth medium contained four strains of Pseudomonas aeruginosa was measured. It allowed to detect the biofilm formation at the QTF after few hours of incubation for all used strains at 106cfu/ml initial concentration (2h for PA01 strain) or 10h for ATCC 27853 strain at 10cfu/ml initial concentration.