Resonant dielectrophoresis and electrohydrodynamics for high-sensitivity impedance detection of whole-cell bacteria

Abstract

We present the co-integration of CMOS-compatible Al/Al2O3 interdigitated microelectrodes (IDEs) with an electrokinetic-driven macroelectrode for sensitive detection of whole-cell bacteria in a microfluidic channel. Two frequency ranges applied to the macroelectrode were identified to notably increase the bacterial coverage of the impedimetric sensor per unit time. Around 10 kHz, the bacterial cells were directed towards the IDE center thanks to AC electroosmosis (AC-EO) and the sensor capacitance linearly increased, achieving a limit of detection (LoD) of 3.5 × 10(5) CFU mL(-1) after an incubation time of 20 min with Staphylococcus epidermidis. At 63 MHz precisely, a resonance effect due to the device was found to dramatically increase the trapping of S. epidermidis on the sensor periphery, due to the combined actions of short-range contactless dielectrophoresis (cDEP) and long-range Joule heating electrothermal (J-ET) flow. Thanks to a flow-based method, the bacterial cells were redirected towards the sensor center and an LoD of 10(5) CFU mL(-1) was achieved within 20 min of incubation, which is almost two orders of magnitude better than the impedimetric sensor alone. Analytical models and 2D simulations using the Maxwell stress tensor (MST) provide a comprehensive analysis of the experimental results, especially about the spectral balance between cDEP, AC-EO and J-ET accounting for the 33-nm thick insulating layer atop the electrodes. Electrode CMOS compatibility confers portability, miniaturization and affordability capabilities for building point-of-care (PoC) diagnostic tests in a lab-on-a-chip (LoC).

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

“…They monitored the changes during the cell cycle and could distinguish the different cell status [9]. Several groups exploited the dielectrophoretic response of various cells for characterisation and separation purposes [17][18][19][20][21][22][23]. Jones et al reported that E. coli of different serotypes could be discriminated by their dielectric response [19].…”

Design and characterization of a passive, disposable wireless AC-electroosmotic lab-on-a-film for particle and fluid manipulation

“…Of the various LOC devices which have followed many are based on electrical methods, including electrophoresis (EP) [3,4] electrowetting on dielectric (EWOD) [5,6] and electrokinetics effects (including dielectrophoresis (DEP) [7][8][9][10] AC electroosmosis (ACEO) [11][12][13][14] and the electrothermal effect [15,16]). These electrical LOCs have found numerous applications in processes such as drug delivery [17][18][19][20][21], cell analysis [22,23], analytical assay [24], and clinical diagnostics [25,26].…”

Emerging Biorecognition and Transduction Schemes for Rapid Detection of Pathogenic Bacteria in Food

“…Over the last 2 decades, much effort has focused on resolving this issue by development of sample pretreatment methods that can be integrated with biosensors. These approaches include microfluidic separation (Zuo and others ; Packard and others ; Clime and others ; Kim and others ; Lee and others ; Luka and others ; Gashti and others ), nanoparticle separation (Varshney and Li ; Kwon and others ; Wang and others ), magnetic relaxation switching (Chen and others ), dielectrophoresis (Cheng and others ; Packard and others ; Wang and others ; Yang ; Hamada and others ; Couniot and others ; Kim and others ; Fernandez and others ), immunochromatography (Vyas and others ), acoustofluidic sorting (Li and others ), ferrofluidic manipulation (Kose and others ), or hydrodynamic focusing (Clime and others ). Although not reviewed in detail here, sample pretreatment is a major focus of biosensor research labs and the primary challenges are minimizing destructive sampling, need for pumps, energy, and use of exogenous chemicals.…”