Development of a hybrid ferrofluid seal technology for miniature pneumatic and hydraulic actuators

Future microrobotic applications require actuators that can generate a high actuation force and stroke in a limited volume. Up to now, little research has been performed on the development of pneumatic and hydraulic microactuators, although they offer great prospects in achieving high force densities. One of the main technological barriers in the development of these actuators is the fabrication of powerful seals with low leakage. This paper presents a seal technology for linear fluidic microactuators based on ferrofluids. A design and simulation method for these seals has been developed and validated by measurements on miniaturized actuator prototypes. These actuators have an outside diameter of 2 mm, a length of 13 mm and have been tested using both pressurized air and water. Our current actuator prototypes are able to operate at pressures up to 1.6 MPa without leakage. At these pressures, forces up to 0.65 N have been achieved. The stroke of the actuators is 10 mm. © 2009 Elsevier B.V. All rights reserved.

A ferrofluid seal technology for fluidic microactuators

Recent research revealed that microacruators driven by pressurized fluids are able to generate high power and force densities at microscale. Despite these promising properties, fluidic actuators are rare in microsystem technology. The main technological barrier in the development of these actuators is the fabrication of powerful seals with low leakage. This paper presents a seal technology for linear fluidic microacruators based on ferrofluids. An accurate design method for these seals has been developed and validated by measurements on miniaturized actuator prototypes. Our current actuator prototypes are able to seal pressures up to 16 bar without leakage. The actuator has an outside diameter of 2 mm, a length of 13 mm and the actuator is able to generate forces of 0.65 N and a stroke of 10 mm. Moreover, promising properties such as the restoration of the seal after a pressure overload have been observed.