title: Thermoosmotic microfluidics.
abstract: Microchannels with asymmetrically ratcheted walls are here shown to behave as effective and versatile microfluidic pumps if locally heated. When the boundary walls have different temperatures, the confined liquid experiences a temperature gradient along the sawtooth edges, which can induce a thermoosmotic flow. A mesoscale molecular simulation approach is here employed to investigate the flows which are contrasted using an analytical approach. Microchannels can be composed by one or two ratcheted walls which can be straight or cylindrical. Varying the channel geometry can not only change the overall fluid flux, but also vary the flow patters from shear to capillary type, or even to extensional type flows. This scheme does not require multiphase fluids or any movable channel parts, although they are possible to be implemented. The proposed principle is then very versatile to locally manipulate complex fluids, and a promising tool to recover waste heat, to facilitate cooling of microchips, and to manufacture portable lab-on-a-chip devices.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics and Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. mcyang@iphy.ac.cn.
authors.forename: Mingcheng
authors.initials: M
authors.lastname: Yang
authors.affiliation: Theoretical Soft-Matter and Biophysics, Institute of Complex Systems, Forschungszentrum Jülich, 52425 Jülich, Germany. m.ripoll@fz-juelich.de.
authors.forename: Marisol
authors.initials: M
authors.lastname: Ripoll