Rensselaer Polytechnic Institute engineering researchers have developed pistons, in which oscillating droplets of ferrofluid can be used to pump small volumes of liquid. They can also function as liquid lenses that vibrate at high speeds and move in and out of focus as they change shape.
Pulses from an electromagnet provoke one of the ferrofluid droplets, the driver, to vibrate back and forth. This vibration, in turn, prompts a combination of magnetic, capillary, and inertial forces that cause the second droplet to vibrate in an inverted pattern. The two droplets create a piston, resonating back and forth with great speed and a spring-like force. Researchers can finely control the strength and speed of these vibrations by exposing the driver ferrofluid to different magnetic fields. By passing light through these droplets, the device is also transformed into a miniature camera lens. As the droplets move back and forth, the lens automatically changes its focal length.
The research team is confident that the new discovery can be exploited to create a host of new devices, including micro displacement pumps, liquid switches, adaptive lenses, and advanced drug delivery systems.
Also: Learn about drug delivery and dispensing.