title: Design of turbulent tangential micro-mixers that mix liquids on the nanosecond time scale.
abstract: Unravelling (bio)chemical reaction mechanisms and macromolecular folding pathways on the (sub)microsecond time scale is limited by the time resolution of kinetic instruments for mixing reactants and observation of the progress of the reaction. To improve the mixing time resolution, turbulent four- and two-jet tangential micro-mixers were designed and characterized for their mixing and (unwanted) premixing performances employing acid-base reactions monitored by a pH-sensitive fluorescent dye. The mixing performances of the micro-mixers were determined after the mixing chamber in a free-flowing jet. The premixing behavior in the vortex chamber was assessed in an optically transparent glass-silicon replica of a previously well-characterized stainless-steel four-jet tangential micro-mixer. At the highest flow rates, complete mixing was achieved in 160ns with only approximately 9% premixing of the reactants. The mixing time of 160ns is at least 50 times shorter than estimated for other fast mixing devices. Key aspects to the design of ultrafast turbulent micro-mixers are discussed. The integration of these micro-mixers with an optical flow cell would enable the study of the very onset of chemical reactions in general and of enzyme catalytic reactions in particular.
authors.affiliation: Laboratory of Biotechnology, Delft University of Technology, 2628 BC Delft, The Netherlands.
authors.forename: Sandra
authors.initials: S
authors.lastname: Mitic
authors.affiliation: BIOS/Lab-on-a-Chip group, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology, University of Twente, 7500 AE Enschede, The Netherlands.
authors.forename: Jan W
authors.initials: JW
authors.lastname: van Nieuwkasteele
authors.affiliation: BIOS/Lab-on-a-Chip group, MESA+ Institute for Nanotechnology and MIRA Institute for Biomedical Technology, University of Twente, 7500 AE Enschede, The Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: van den Berg
authors.affiliation: Laboratory of Biotechnology, Delft University of Technology, 2628 BC Delft, The Netherlands. Electronic address: s.devries@tudelft.nl.
authors.forename: Simon
authors.initials: S
authors.lastname: de Vries
mesh_terms: D004867:Equipment Design; D005456:Fluorescent Dyes / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods; D036103:Nanotechnology; D012825:Silicon / Q000737:chemistry; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D012825:Silicon
keywords: Biocatalysis; Kinetics; Ultrafast mixing