title: Hybrid electrokinetic manipulation in high-conductivity media.
abstract: This study reports a hybrid electrokinetic technique for label-free manipulation of pathogenic bacteria in biological samples toward medical diagnostic applications. While most electrokinetic techniques only function in low-conductivity buffers, hybrid electrokinetics enables effective operation in high-conductivity samples, such as physiological fluids (∼1 S m(-1)). The hybrid electrokinetic technique combines short-range electrophoresis and dielectrophoresis, and long-range AC electrothermal flow to improve its effectiveness. The major technical hurdle of electrode instability for manipulating high conductivity samples is tackled by using a Ti-Au-Ti sandwich electrode and a 3-parallel-electrode configuration is designed for continuous isolation of bacteria. The device operates directly with biological samples including urine and buffy coats. We show that pathogenic bacteria and biowarfare agents can be concentrated for over 3 orders of magnitude using hybrid electrokinetics.
authors.affiliation: Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, Arizona 85721, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Gao
authors.forename: Mandy L Y
authors.initials: ML
authors.lastname: Sin
authors.forename: Tingting
authors.initials: T
authors.lastname: Liu
authors.forename: Vincent
authors.initials: V
authors.lastname: Gau
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Liao
authors.forename: Pak Kin
authors.initials: PK
authors.lastname: Wong
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D004553:Electric Conductivity; D004566:Electrodes; D004586:Electrophoresis / Q000295:instrumentation* / Q000379:methods; D006046:Gold / Q000737:chemistry; D007700:Kinetics; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods; D014025:Titanium / Q000737:chemistry
chemical_list: D006046:Gold; D014025:Titanium