Originally Published EMDM September 2002
INDUSTRY NEWS
World's Smallest Hollow-Shaft Actuator Introduced
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| A miniature servo actuator is suited for precisely metering fluids in drug-delivery devices and positioning endoscope lenses. (click to enlarge) |
At the 2001 Hannover Fair, Micromotion GmbH (Mainz, Germany) caused a small sensation when it introduced a microdrive incorporating what it claimed was the world's tiniest backlash-free gear. Building on this innovation, the company returned to the event's newly christened microtechnology section this year to premiere its miniature hollow-shaft servo actuator. Medical devices represent a core application for the product, according to managing director Rolf Slatter.
The actuator combines a hollow-shaft microdrive with an electrically commutated brushless 1.2-W miniature motor that was developed in partnership with Maxon Motor AG (Sachseln, Switzerland). The microgear assembly is so small—it has a 1-mm axial length and an outer diameter of 8 mm—that two of them could fit on a coin. The axial dimensions of the servo actuator and motor are 31.3 mm.
Performance specifications include 5-mN∙m output torque, a reduction ratio of 160:1, and output speeds up to 200 rpm. Despite the high reduction ratio, the assembly has only six metal components, thus enhancing its robustness and reliability.
Attaining 10 arc seconds repeatability, the actuator is suited for a variety of positioning applications in which precise alignment or adjustment of tiny components, backlash-free operation, and repeatability and reliability are required. Optical fibres, air or vacuum flow, or a laser beam can be passed through the component's 0.65-mm-diam hollow shaft. Slatter cites a host of promising medical applications for the component.
"One key application that we see is in microdosing equipment, such as portable insulin and protein pumps," says Slatter. "The costly fluid is metered in nanolitre quantities," he adds, "which requires very small and accurate actuator steps. Much smaller implantable versions of the devices that are under development would benefit even more from the microdrive."
For more information, contact Micromotion GmbH, An der Fahrt 13, D-55124 Mainz, Germany; phone: +49 6131 669270; fax: +49 6131 6692720.
Copyright ©2002 European Medical Device Manufacturer
