Combined dielectrophoretic and impedance system for on-chip controlled bacteria concentration: Application to Escherichia coli.
The present paper reports a bacteria autonomous controlled concentrator prototype with a user-friendly interface for bench-top applications. It is based on a microfluidic lab-on-a-chip and its associated custom instrumentation, which consists of a dielectrophoretic actuator, to preconcentrate the sample, and an impedance analyzer, to measure concentrated bacteria levels. The system is composed of a single microfluidic chamber with interdigitated electrodes and an instrumentation with custom electronics. The prototype is supported by a real-time platform connected to a remote computer, which automatically controls the system and displays impedance data used to monitor the status of bacteria accumulation on-chip. The system automates the whole concentrating operation. Performance has been studied for controlled volumes of Escherichia coli samples injected into the microfluidic chip at constant flow rate of 10 μL/min. A media conductivity correcting protocol has been developed, as the preliminary results showed distortion of the impedance analyzer 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. Furthermore, the impedance monitoring protocol had been adjusted and optimized, to handle changes in the electrical properties of the bacteria media over time.
Department of Electronics, University of Barcelona, Barcelona, Spain.
Beatriz
B
Del Moral-Zamora
Department of Electronics, University of Barcelona, Barcelona, Spain.
Jaime
J
Punter-Villagrassa
Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.
Ana M
AM
Oliva-Brañas
Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.
Juan Manuel
JM
Álvarez-Azpeitia
Department of Electronics, University of Barcelona, Barcelona, Spain.
Jordi
J
Colomer-Farrarons
Department of Electronics, University of Barcelona, Barcelona, Spain.|Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.|Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, Spain.
Josep
J
Samitier
Department of Electronics, University of Barcelona, Barcelona, Spain.|Nanobioengineering Group, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain.|Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Zaragoza, Spain.
Antoni
A
Homs-Corbera
Department of Electronics, University of Barcelona, Barcelona, Spain.
Pere Ll
PL
Miribel-Català
D017097:Electric Impedance; D004566:Electrodes; D004586:Electrophoresis / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D004926:Escherichia coli / Q000302:isolation & purification* / Q000502:physiology; D005240:Feasibility Studies; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*
Autonomous device; Bacteria concentrator; Dielectrophoresis; Escherichia coli; Impedance analysis