This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The development of a novel electromagnetically (EM) actuated stirring method, for use in
microbioreactors, is reported. Mixing in microbioreactors is critical to ensure even distribution of nutrients to
microorganisms and cells. Magnetically driven stirrer bars or peristaltic mixing are the most commonly
utilised mixing methods employed in completely liquid-filled microbioreactors. However the circular reactor
shape required for mixing with a stirrer bar and frequently used for peristaltically mixed microbioreactors
presents difficulties for bubble-free priming in a microfluidic bioreactor. Moreover the circular shape and the
hardware required for both types of mixing reduces the potential packing density of multiplexed reactors. We
present a new method of mixing, displaying design flexibility by demonstrating mixing in circular and
diamond-shaped reactors and a duplex diamond reactor and fermentation of the gram-positive bacteria S.
carnosus in a diamond-shaped microbioreactor system. The results of the optimisation of this mixing
method for performing fermentations alongside both batch and continuous culture fermentations are
presented