Combined Dielectrophoresis and Impedance Systems for Bacteria Analysis in Microfluidic On-Chip Platforms

Abstract

Bacteria concentration and detection is time-consuming in regular microbiology procedures aimed to facilitate the detection and analysis of these cells at very low concentrations. Traditional methods are effective but often require several days to complete. This scenario results in low bioanalytical and diagnostic methodologies with associated increased costs and complexity. In recent years, the exploitation of the intrinsic electrical properties of cells has emerged as an appealing alternative approach for concentrating and detecting bacteria. The combination of dielectrophoresis (DEP) and impedance analysis (IA) in microfluidic on-chip platforms could be key to develop rapid, accurate, portable, simple-to-use and cost-effective microfluidic devices with a promising impact in medicine, public health, agricultural, food control and environmental areas. The present document reviews recent DEP and IA combined approaches and the latest relevant improvements focusing on bacteria concentration and detection, including selectivity, sensitivity, detection time, and conductivity variation enhancements. Furthermore, this review analyses future trends and challenges which need to be addressed in order to successfully commercialize these platforms resulting in an adequate social return of public-funded investments.

Review: Microbial analysis in dielectrophoretic microfluidic systems

“…While the label-free characteristic of DEP manipulation has traditionally enabled sample preparation for detection of molecular nucleic-acid type biomarkers by enhancing capture efficiency and selectivity for impedance-based detection, current trends are directed towards the application of DEP within miniaturized point-of-care type microbial concentration 225,226 and sensing devices 227 . A prime example of this is the commercialization of the DEPIM technology by Panasonic Healthcare in the form of a microbial counter for dental applications.…”

Dielectrophoretic analysis of the impact of isopropyl alcohol on the electric polarisability of Escherichia coli whole-cells

“…Changes in the dielectricity or conductivity, as for dead cells, membrane truncation or different cell phases, affect the electrical impedance and the dielectrophoretic migration, and thus can be detected [8][9][10][11]. Dielectrophresis is the migration of an electrically polarisable object in an inhomogeneous electric field.…”

Improvement of Depth Profiling into Biotissues Using Micro Electrical Impedance Spectroscopy on a Needle with Selective Passivation

“…EIS (electrical impedance spectroscopy) devices have been widely employed in biological studies, such as single cell analysis [1,2,3,4,5,6,7,8,9] and virus detection [10,11,12,13,14,15]. In particular, many studies have reported significant differences in electrical impedance between dissimilar cells or tissues from various organs [16,17,18,19,20,21,22,23,24,25].…”