title: Fabrication and evaluation of a 3-dimensional microchip device where carbon microelectrodes individually address channels in the separate fluidic layers.
abstract: A fabrication method that results in a 3-dimensional fluidic device containing poly(dimethylsiloxane) (PDMS) -embedded microelectrodes that individually address each layer is described. The two electrode-containing layers and the polycarbonate membrane are reversibly sealed together, eliminating the need for plasma oxidation during device assembly, while enabling simultaneous amperometric detection in membrane-separated fluidic channels. The electrodes were characterized using microchip-based flow analysis. It was found that PDMS-embedded electrodes have a limit of detection (400 nM for catechol) that is 5-fold lower than that reported for microchip-based flow analysis with similar electrodes in a hybrid PDMS-glass device. The selectivity of the carbon ink microelectrodes can be tuned by a simplified modification procedure; this was demonstrated by the selective detection of nitric oxide over possible interferents. Finally, the ability to monitor processes occurring in separate layers of a 3-dimensional device was shown by the simultaneous detection of catechol on either side of the polycarbonate membrane. The electrode response in each fluidic channel was found to be linear as a function of concentration and the transport between layers could be controlled by varying the linear velocities of each fluidic channel. The ability to fabricate and operate this type of 3-dimensional device will be useful for the development of cell-based in vivo mimics that involve the transport of molecular messengers and/or pharmaceuticals across layers of immobilized cells.
authors.affiliation: Saint Louis University, Department of Chemistry, 3501 Laclede Avenue, St. Louis, MO 63103, USA.
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Hulvey
authors.forename: Luiza I
authors.initials: LI
authors.lastname: Genes
authors.forename: Dana M
authors.initials: DM
authors.lastname: Spence
authors.forename: R Scott
authors.initials: RS
authors.lastname: Martin
mesh_terms: D002244:Carbon; D004129:Dimethylpolysiloxanes; D056656:Lab-On-A-Chip Devices; D008839:Microelectrodes; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D012828:Silicones
chemical_list: D004129:Dimethylpolysiloxanes; D012828:Silicones; C013830:baysilon; D002244:Carbon