On-Demand, Contact-Less and Loss-Less Droplet Manipulation via Contact Electrification.

While there are many droplet manipulation techniques, all of them suffer from at least one of the following drawbacks - complex fabrication or complex equipment or liquid loss. In this work, a simple and portable technique is demonstrated that enables on-demand, contact-less and loss-less manipulation of liquid droplets through a combination of contact electrification and slipperiness. In conjunction with numerical simulations, a quantitative analysis is presented to explain the onset of droplet motion. Utilizing the contact electrification technique, contact-less and loss-less manipulation of polar and non-polar liquid droplets on different surface chemistries and geometries is demonstrated. It is envisioned that the technique can pave the way to simple, inexpensive, and portable lab on a chip and point of care devices.