Increased Sensitivity of Love Wave Delay-Lines for Heavy Metal Detection through the Deposition of a Mesoporous TiO2Coating

This work deals with the design of a highly sensitive biosensor for heavy metal detection in liquid medium. The developed biosensor consists in an acoustic Love wave sensor with polyelectrolyte multilayers (PEM) and E.coli bacteria as bioreceptors. The PEM represent a versatile polymeric matrix, deposited with an efficient "layer-by-layer" method. Bacteria are immobilized on the PEM, and are used to detect the presence of cadmium because of the modification of their viscoelastic properties induced by heavy metals. The PEM and bacteria deposition, as well as the detection of cadmium are measured through the real-time resonant frequency shifts of the sensor. The impact of the addition of a mesoporous TiO2 layer between the Love wave guiding layer and the PEM has been studied. The subsequent results are compared to those obtained with a "classic" Love wave device (Quartz + SiO2) and highlight an increased sensitivity of the acoustic platform towards cadmium.