title: Microfluidic tool box as technology platform for hand-held diagnostics.
abstract: BACKGROUND
  Use of microfluidics in point-of-care testing (POCT) will require on-board fluidics, self-contained reagents, and multistep reactions, all at a low cost. Disposable microchips were studied as a potential POCT platform.
  
  
  METHODS
  Micron-sized structures and capillaries were embedded in disposable plastics with mechanisms for fluidic control, metering, specimen application, separation, and mixing of nanoliter to microliter volumes. Designs allowed dry reagents to be on separate substrates and liquid reagents to be added. Control of surface energy to +/-5 dyne/cm2 and mechanical tolerances to < or = 1 microm were used to control flow propulsion into adsorptive, chromatographic, and capillary zones. Fluidic mechanisms were combined into working examples for urinalysis, blood glucose, and hemoglobin A(1c) testing using indicators (substances that react with analyte, such as dyes, enzyme substrates, and diazonium salts), catalytic reactions, and antibodies as recognition components. Optical signal generation characterized fluid flow and allowed detection.
  
  
  RESULTS
  We produced chips that included capillary geometries from 10 to 200 microm with geometries for stopping and starting the flow of blood, urine, or buffer; vented chambers for metering and splitting 100 nL to 30 microL; specimen inlets for bubble-free specimen entry and containment; capillary manifolds for mixing; microstructure interfaces for homogeneous transfer into separation membranes; miniaturized containers for liquid storage and release; and moisture vapor barrier seals for easy use. Serum was separated from whole blood in <10 s. Miniaturization benefits were obtained at 10-200 microm.
  
  
  CONCLUSIONS
  Disposable microchip technology is compatible with conventional dry-reagent technology and allows a highly compact system for complex assay sequences with minimum manual manipulations and simple operation.
authors.affiliation: Diagnostic Division, Bayer Healthcare LLC, Tarrytown, NY, USA. michael.pugia.b@bayer.com
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Pugia
authors.forename: Gert
authors.initials: G
authors.lastname: Blankenstein
authors.forename: Ralf-Peter
authors.initials: RP
authors.lastname: Peters
authors.forename: James A
authors.initials: JA
authors.lastname: Profitt
authors.forename: Klaus
authors.initials: K
authors.lastname: Kadel
authors.forename: Thomas
authors.initials: T
authors.lastname: Willms
authors.forename: Ronald
authors.initials: R
authors.lastname: Sommer
authors.forename: Hai Hang
authors.initials: HH
authors.lastname: Kuo
authors.forename: Lloyd S
authors.initials: LS
authors.lastname: Schulman
mesh_terms: D001786:Blood Glucose / Q000032:analysis; D004867:Equipment Design; D006442:Glycated Hemoglobin / Q000032:analysis*; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods*; D019095:Point-of-Care Systems; D012680:Sensitivity and Specificity; D013499:Surface Properties; D016482:Urinalysis / Q000295:instrumentation
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin