Magnetic levitation of a ferrofluid droplet in mid-air

Abstract

A prototype magnetic levitation (maglev) system for feeding, holding and conveying ferrofluids successfully levitated a ferrofluid droplet with feedback control in the air at room temperature. This maglev system consists of a rod-shaped electromagnet, a displacement sensor, an oil-repellent film, a sample stage, and peripheral control devices. The levitated droplet has a mass of 15 mg and a viscosity of 5,000 mPa.sec. The pure deformation and behavior of the droplet in the process from the control start to the stable levitation state were investigated in detail using a high-speed camera. The magnetically levitated droplet behaved very fast as well as a common solid object. The droplet finally stabilized in a bottom-swollen egg shape in mid-air. The technique of magnetically levitating one droplet will lead to developing a manipulator system for ferrofluids.