Rapid ESKAPE Pathogens Detection Method using Tapered Dielectrophoresis Electrodes via Crossover Frequency Analysis

Abstract

This paper introduces the versatile of an electrokinetic technique by using the non-uniform electric field for dielectrophoresis (DEP) application. This technique is defined as electromicrofluidics. The potential application for portable and real time detection method of Enterococcus faecium (EF), Staphylococcus aureus (SA), Klebsiella pneumoniae (KP), Acinetobacter baumannii (AB), Pseudomonas aeruginosa (PA) and Enterobacter aerogenes (EA), which are the (ESKAPE) bacteria. The MATLAB analytical modelling was used in simulating the polarisation factor and velocities of bacteria based on Clausius-Mossotti factor (CMF). The validation of CMF simulation through the DEP experimental can be quantified based on the response of alternating current (AC) voltage applied using 6 voltage peak to peak (Vp-p) to their input frequencies from 100 to 15000 kHz. The droplet method was deployed to place properly 0.2 μL of sample onto DEP microelectrode. The velocities and crossover frequency (fxo) ranges of bacteria were determined through bacteria trajectory in specific time interval monitored by microscope attached with eyepiece camera. The applied range of input frequencies from 100 to 15000 kHz at 6 Vp-p for each bacteria were successfully identified the unique ranges of frequencies response for detection application. The advantages of this works are selective with rapid capability for multidrug resistant (MDR) bacteria detection application.

Dielectrophoresis microbial characterization and isolation of Staphylococcus aureus based on optimum crossover frequency

“…The particles are temporarily polarized and move toward increasing or decreasing field intensity based on permittivity and conductivity differences between the particles and medium. In general, the DEP force (F DEP ) is determined by the physical and electrical properties of the particles and the medium and described by the following equation [24, 25]: $$$$\begin{equation}{\rm{\;}}{{\rm{F}}_{{\rm{DEP}}}} = \;2\pi r_{ext}^3{\varepsilon _0}{\varepsilon _m}\;Re\left[ {{f_{CM}}} \right]\nabla {E^2}\end{equation}$$$$where $${r_{ext}}$$ is the particle radius, ε 0 is the permittivity for vacuum (8.854 × 10 –12 F/m), $${\varepsilon _m}$$ is the relative permittivity of the suspending medium, $$Re[ {{f_{CM}}} ]$$ is the real part of the Clausius–Mossotti factor (CMF) of the particle, and $$\nabla {E^2}$$ defines the gradient of the external field magnitude square. The real part of $${f_{CM}}$$ for a spherical particle is described by the following equation, which depends on medium complex permittivity, $$\varepsilon _m^*$$, and the second effective complex permittivity of the particle, $$\varepsilon _{eff2}^*$$ [25]: …”

“…The first effective complex permittivity, $$\varepsilon _{eff1\;}^{*\;}$$, depends on the permittivity of the bacteria core, inside of the cytoplasmic region, $$\varepsilon _c^*$$, and the permittivity of the inner shell, $$\varepsilon _{s1\;}^{*\;}$$, as described by the following equation [24, 25]: $$$$\begin{equation}\varepsilon _{eff1\;}^{*\;}\; = \;\varepsilon _{s1\;}^{*\;}\;\frac{{{{\left( {\frac{{{r_2}}}{{{r_1}}}} \right)}^3} + 2\;\frac{{{\varepsilon _c}^* - {\varepsilon _{s1}}^*}}{{{\varepsilon _c}^* - 2{\varepsilon _{s1}}^*}}}}{{{{\left( {\frac{{{r_2}}}{{{r_1}}}} \right)}^3} - \;\frac{{{\varepsilon _c}^* - {\varepsilon _{s1}}^*}}{{{\varepsilon _c}^* + 2{\varepsilon _{s1}}^*}}}}\end{equation}$$$$where r 1 and r 2 are the inner and outer shells of the bacteria. The second effective complex permittivity, $$\varepsilon _{eff2\;}^{*\;}$$, is then derived by considering the first effective complex permittivity, …”

“…The particles are temporarily polarized and move toward increasing or decreasing field intensity based on permittivity and conductivity differences between the particles and medium. In general, the DEP force (F DEP ) is determined by the physical and electrical properties of the particles and the medium and described by the following equation [24,25]:…”

“…The traditional method of diagnosing a patient's infection relies on culturing bacteria and conducting an antibiotic susceptibility test. Due to limitations of the technique with the evolution of bacteria, especially antibiotic resistance bacteria, lab-based testing has faced severe disadvantages and incurred wastages in the form of culture agars and incorrect bacterial infection diagnoses [23][24][25]. The classification of antibiotic resistance bacteria needs to be developed to become a powerful technology for the bacteria's characterization.…”

“…Therefore, the relevance of real-time detection of sensitive and specific techniques that can detect, manipulate, and observe the bacteria cells is vital to differentiate the bacteria based on their properties. Several studies have revealed the development of microbial analysis of microfluidic biosensors and technology for detecting biological samples [22,23], particularly bacteria, using DEP [24,25].…”