title: Optofluidic guiding, valving, switching and mixing based on plasmonic heating in a random gold nanoisland substrate.
abstract: We present a versatile optofluidic flow manipulation scheme based on plasmonic heating in a random gold nanoisland substrate (Au-NIS). With its highly efficient conversion of optical power to hydrodynamic actuation, the reported substrate is used for laser-controlled optofluidic manipulation. It is the first time that microfluidic flow guiding, valving, and mixing within the same functional substrate has been realised. Plasmonic heating provides power for guiding the sample flow inside a microfluidic channel at controlled speed and transport of small particles or living cells is demonstrated. We have also made a laser-actuated microfluidic valve through controlling the surface wettability of the sample/Au-NIS interface. When the laser power density is sufficiently high to generate a bubble, localized convection around the bubble can lead to efficient sample mixing within a microfluidic chamber. The reported Au-NIS scheme practically offers a programmable functional surface on which users have the freedom to control the wetting characteristics with a focused laser beam. We have verified that this optofluidic approach induces insignificant degradation in cell viability. The reported scheme therefore offers a wide range of application possibilities in microfluidics and biomedical engineering, particularly those operated under a low Reynolds number.
authors.affiliation: Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, PR China. hpho@ee.cuhk.edu.hk.
authors.forename: Jiajie
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, PR China. hpho@ee.cuhk.edu.hk.
authors.forename: Zhiwen
authors.initials: Z
authors.lastname: Kang
authors.affiliation: Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, PR China. hpho@ee.cuhk.edu.hk.|Institute of Optical Communication Engineering, Nanjing University, Nanjing, 210093, PR China.
authors.forename: Guanghui
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Biochemistry, The Chinese University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Jacky
authors.identifier: http://orcid.org/0000-0002-0355-8865
authors.initials: J
authors.lastname: Loo
authors.affiliation: Department of Biochemistry, The Chinese University of Hong Kong, Hong Kong SAR, PR China.
authors.forename: Siu Kai
authors.initials: SK
authors.lastname: Kong
authors.affiliation: Department of Electronic Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong, PR China. hpho@ee.cuhk.edu.hk.
authors.forename: Ho-Pui
authors.initials: HP
authors.lastname: Ho
mesh_terms: D004867:Equipment Design; D004926:Escherichia coli; D006046:Gold / Q000737:chemistry*; D006358:Hot Temperature; D050296:Microbial Viability; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D049329:Nanostructures / Q000737:chemistry*; D055095:Optics and Photonics / Q000295:instrumentation*
chemical_list: D006046:Gold