title: Single potential electrophoresis microchip with reduced bias using pressure pulse injection.
abstract: We propose two variants of a new injection technique for use in electrophoresis microchips, called "front gate pressure injection" and "back gate pressure injection", that both enable a controlled and reproducible sample introduction with reduced bias compared to electrokinetic gated injection. A continuous flow of a test solution of fluorescein/rhodamine B in 20 mM Tris/boric acid buffer (pH 8.6) sample test solution is electrokinetically driven near to the entrance of the separation channel, using a single voltage (3 kV) that is constant in time. A sample plug is injected in the separation channel by a pressure pulse of the order of 0.1 s. The latter is generated using the mechanical deflection of a PDMS membrane that is loosely placed on a dedicated chip reservoir. The analysis of the peak area ratio of the separated compounds demonstrates a nearly constant sample composition when using pressure-based injection. A small remaining injection bias for the shortest membrane deflection times can be attributed to a dilution effect of the charged compound due to the presence of an electrical field transverse to the sample flow boundary in the channel junction.
authors.affiliation: Institute of Microelectronics and Microsystems, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland. Frederic.Lacharme@epfl.ch
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lacharme
authors.forename: Martin A M
authors.initials: MA
authors.lastname: Gijs
mesh_terms: D004129:Dimethylpolysiloxanes / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000379:methods*; D046209:Electrophoresis, Microchip / Q000379:methods*; D017022:Flow Injection Analysis / Q000379:methods*; D011312:Pressure
chemical_list: D004129:Dimethylpolysiloxanes