Wetting ridge-assisted programmed (WRAP) drop actuation published in Nature Communications.
Researchers from the City University of Hongkong, the Chinese Academy of Science and PCF have published an approach to manipulating droplets on structured surfaces that are infused with a ferrofluid. Unlike conventional digital microfluidics approaches that exert a force on the droplet of the surface, the WRAP (wetting-ridge-assisted programmed) actuation mechanism is based on pulling using magnetic fields on the so-called wetting ridges of the infusion liquid. In this way, the actuation becomes completely independent of the composition actuated droplet. In fact, even solid residues of dried droplets could be manipulated. Next to efficient directed droplet transport, the authors demonstrated all other elementary digital droplet operations, namely droplet splitting and merging as well as elementary biochemical reactions, making WRAP a fully functional novel platform technology for digital microfluidics.
