Magnetically driven droplet manipulation on a smart surface prepared by electrospinning

Abstract

Droplet manipulation using a magnetic field has vital applications in nanomaterials synthesis, lab-on-a-chip, and other domains. To address the separation issue between the droplet and the magnetic particle following the manipulation process, electrospinning technology was used to create a thermosensitive surface with changeable hydrophilicity. The droplet manipulation in this investigation could be divided into three steps: Step 1, the iron shot entered the droplet; Step 2, the iron shot carried the droplet forward; Step 3, the iron shot exited the droplet. The experimental findings revealed that a part of the iron shots could carry droplets with varying sizes when a magnetic field was activated. At the same time, droplet manipulation would be difficult employing high velocity iron shot movement or in a low temperature environment. Further investigation revealed two conditions for successful droplet manipulation. Firstly, the diameter of the iron shot had to be large enough to create adequate capillary force. Secondly, the hysteresis force between the droplet and the smart surface changed with the alteration of the hydrophilicity of the smart surface. More experiments indicated that the proposed droplet manipulation approach was also capable of achieving droplet transport on a slope, multi-droplets transport, and multi-droplets synthesis.