Tiny actuators have no moving parts (but one)

Nanomuscle actuators use the properties of shape-memory alloys to create tiny actuators that can be produced at a fraction of the size and cost of traditional electric motors.

Addressing the large applications gap between macroscopic motors and microelectromechanical systems, Nanomuscle actuators from Steadlands International use the properties of shape-memory alloys to create tiny actuators that can be produced at a fraction of the size and cost of traditional electric motors.

In contrast to the coils, magnets and gears used in a motor-powered actuator, the Nanomuscle has a single working part - a long, hair-thin wire of nickel-titanium alloy.

When a current passes through the wire, the resistive heating of the current causes the wire to contract, providing the basic actuation function.

The actuator moves through a distance of 4mm and develops a force of 70g, yet the entire device is only the size of a paper clip and operates from a 4V supply using only 470mA.

To maintain constant and reliable movement, individual filaments are fitted to a series of small, stacked metal plates that slide over one another.

The movement of the plates is then controlled by a built-in microprocessor to achieve repeatable and smooth movement.

Potential heating problems have been overcome with the addition of a miniature cooling system.

The Nanomuscle is ideally suited to applications such as toys, medical devices, read/write head mechanisms in disk drives, disk ejection mechanisms in computers, and automotive applications such as mirror-adjusting mechanisms.

(This was Engineeringtalk's Top Story on 14 June 2002).

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