title: Electromagnetic stirring in a microbioreactor with non-conventional chamber morphology and implementation of multiplexed mixing.
abstract: BACKGROUND
  Microbioreactors have emerged as novel tools for early bioprocess development. Mixing lies at the heart of bioreactor operation (at all scales). The successful implementation of micro-stirring methods is thus central to the further advancement of microbioreactor technology. The aim of this study was to develop a micro-stirring method that aids robust microbioreactor operation and facilitates cost-effective parallelization.
  
  
  RESULTS
  A microbioreactor was developed with a novel micro-stirring method involving the movement of a magnetic bead by sequenced activation of a ring of electromagnets. The micro-stirring method offers flexibility in chamber designs, and mixing is demonstrated in cylindrical, diamond and triangular shaped reactor chambers. Mixing was analyzed for different electromagnet on/off sequences; mixing times of 4.5 s, 2.9 s, and 2.5 s were achieved for cylindrical, diamond and triangular shaped chambers, respectively. Ease of micro-bubble free priming, a typical challenge of cylindrical shaped microbioreactor chambers, was obtained with a diamond-shaped chamber. Consistent mixing behavior was observed between the constituent reactors in a duplex system.
  
  
  CONCLUSIONS
  A novel stirring method using electromagnetic actuation offering rapid mixing and easy integration with microbioreactors was characterized. The design flexibility gained enables fabrication of chambers suitable for microfluidic operation, and a duplex demonstrator highlights potential for cost-effective parallelization. Combined with a previously published cassette-like fabrication of microbioreactors, these advances will facilitate the development of robust and parallelized microbioreactors. © 2015 The Authors.Journal of Chemical Technology & Biotechnologypublished by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
authors.affiliation: School of Engineering and Technology University of Hertfordshire UK.
authors.forename: Christabel Kl
authors.initials: CK
authors.lastname: Tan
authors.affiliation: Department of Biochemical Engineering University College London UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Davies
authors.affiliation: School of Engineering and Technology University of Hertfordshire UK.
authors.forename: Daniel K
authors.initials: DK
authors.lastname: McCluskey
authors.affiliation: School of Engineering and Technology University of Hertfordshire UK.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Munro
authors.affiliation: Department of Biochemical Engineering University College London UK.
authors.forename: Mauryn C
authors.initials: MC
authors.lastname: Nweke
authors.affiliation: School of Engineering and Technology University of Hertfordshire UK.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Tracey
authors.affiliation: Department of Biochemical Engineering University College London UK.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Szita
keywords: electromagnetic actuation; microbioreactor; microfluidics priming; mixing; multiplexing