Li, DongqingLi, Mengqi2017-02-082017-02-082016-05-18http://dx.doi.org/10.1007/s11051-016-3390-5http://hdl.handle.net/10012/11290The final publication is available at Springer via http://dx.doi.org/ 10.1007/s11051-016-3390-5.Janus droplets with two opposite faces of different physical or chemical properties have great potentials in many fields. This paper reports a new method for making Janus droplets by covering one side of the droplet with charged nanoparticles in an externally applied DC electric field. In this paper, aluminum oxide nanoparticles on micro-sized and macro-sized oil droplets were studied. In order to control the surface area covered by the nanoparticles on the oil droplets, the effects of the concentration of nanoparticle suspension, the droplet size as well as the strength of electric field on the final accumulation area of the nanoparticles are studied.enJanus dropletCharged nanoparticlesElectrical fieldParticle redistributionOil droplet in waterArticle