Enhanced bio-inspired microsensor based on microfluidic/bacterial/love wave hybrid structure for continuous control of heavy metals toxicity in liquid medium

Environmental pollution by toxic heavy metals (HM)presents a real threat for aquatic medium and human health. Therefore aquatic ecosystem mangement requires early warning systems for on line monotoring. Microtechmologies can give rise to innovative bio-inspired hybrid microsensors,likely to meet this need and providing cost reductiond by reducing reagents consumption and manufactrring cost. This work deals with a bacteria-based Love wave sensor,with enhanced properties provided by integration of a poludimethylsiloxane (PDMS) microfuidic network for a better contyrol of the sample flow and devoted to in situ monitoring of Cd(II) and Hg(II).Whole Escherichia coli (E.coli) bacteria are used as bioreceptor, mimicking in vivo enzymatic activity. They were immobilized on polyelectrolyte multilayer (PEM) films realized using layer by layer technique (LbL) with alternatively adsorption of positive and negative chains. The acoustic delay line was inserted into as electrones oscillation loop for real time monitoring. Compared to previous work, this paper deepens the results obtained with two types of microfluidic chips (measurements in static and dynamic modes), including analysis in terms of reproducibility. These results are analyzed and interpreted thoroughly leading to assumptions about the phenomena involved in the detection mechanisms. These hypotheses are validated through a pioneering study with atomic force microscopy (AFM), performed to characterize bacteria adhesion and to establish the relationship between bacteria morphological evolution and mechanical properties. APM was chosen for its ability to maintain the bacteria alive during the experience without inducing irreversible damage. The resulting microsystem led to efficient HM detection, characterized by a 12 M. AFM measurements have demonstrated a high bacterial attachment and the stressing effect of toxic HM on bacterial morphological state. These results are consistent with those obtained from Love wave measurements.(C) 2014 Elsevier B.V. All rights reserved.