Abstract
The handling of droplets in a controlled manner is essential to numerous technological and scientific applications. In this work, we present a new open-surface platform for droplet manipulation based on an array of bendable nozzles that are dynamically controlled by a magnetic field. The actuation of these nozzles is possible thanks to the magnetically responsive elastomeric composite which forms the tips of the nozzles; this is fabricated with Fe3O4 microparticles embedded in a polydimethylsiloxane matrix. The transport, mixing, and splitting of droplets can be controlled by bringing together and separating the tips of these nozzles under the action of a magnet. Additionally, the characteristic configuration for droplet mixing in this platform harnesses the kinetic energy from the feeding streams; this provided a remarkable reduction of 80% in the mixing time between drops of liquids about eight times more viscous than water, i.e., 6.5 mPa/s, when compared against the mixing between sessile drops of the same fluids.
Highlights
Droplet manipulation is the core to many technological and biomedical applications spanning from inkjet printing [1,2,3] and additive manufacture [4,5] to drug development/screening [6,7]diagnostics [8,9,10] and point of care devices [11,12]
We present a new open-surface platform for droplet manipulation based on an array of bendable nozzles that are dynamically controlled by a magnetic field
We have developed a novel platform for droplet manipulation in an open-surface manner
Summary
Droplet manipulation is the core to many technological and biomedical applications spanning from inkjet printing [1,2,3] and additive manufacture [4,5] to drug development/screening [6,7]diagnostics [8,9,10] and point of care devices [11,12]. Several open-surface microfluidic systems have been developed to manipulate individual drops of fluids in a precise manner by dispensing them on specialized substrates; most of these systems rely on electrowetting [13,14,15,16], magnetic fields [17,18,19,20], or surface acoustic waves [21,22] to drive the droplet motion. They are often called “digital-microfluidics” because of the particular operation of the discrete volumes of liquid. Capillarity developed in the porous matrix of paper has been applied to run the “pump-less” motion of fluids
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