Abbreviations: Impedance analysis (IA), escherichia coli (E. coli), digital lock-in (DLIA), analog-to-digital converter (ADC), finite element method (FEM). 2 AbstractThe present paper reports a bacteria autonomous controlled concentrator prototype with a userfriendly interface for bench-top applications. It is based on a micro-fluidic lab-on-a-chip and its associated custom instrumentation, which consists in a dielectrophoretic actuator, to preconcentrate the sample, and an impedance analyser, to measure concentrated bacteria levels.The system is composed by a single micro-fluidic chamber with interdigitated electrodes and custom electronics instrumentation. The prototype is supported by a real-time platform connected to a remote computer which automatically controls the system and displays impedance data which is used to monitor bacteria accumulation status on-chip. The system automates the whole concentrating operation. Performance has been studied for controlled volumes of Escherichia Coli (E. coli) samples injected into the micro-fluidic chip at constant flow rate of 10 µl/min. A media conductivity correcting protocol has been developed, as so as the preliminary results shown the distortion of impedance analyser measurement produced by bacterial media conductivity variations through time. With the correcting protocol, the measured impedance values were related to the quantity of bacteria concentrated with a correlation of 0.988 and a coefficient of variation of 3.1%. Feasibility of E. coli on-chip automated concentration, using the miniaturized system, has been demonstrated and impedance monitoring protocol adjusted and optimized, to handle electrical properties changes of the bacteria media over time.3

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