Appliance Design - October 2008 - (Page 26)

MOTORS The piezo effect produces a hula-hoop action that drives a nut around screw to induce precise motion with the Squiggle motor from New Scale Technologies. pushes the screw in a continuous motion so that the motor can be programmed to move in very small, and very accurate increments. The motor can realize sub-micrometer stepping and velocity control, according to Viggiano. The piezoceramic plates are activated using a twophase electric drive with a fixed frequency and a 90 Deg phase shift. The ultrasonic frequency depends on the motor model and can range from 40 to 200 kHz, but a typical frequency is about 150 kHz. At 150 khz, the 1.55 X 1.55 x 6 mm Squiggle motor can achieve speeds of 10 mm per second and can push 20 grams. At the low end, the motor can be set to move very slowly — nanometers per second, or even nanometers per hour. The top speed is around 7 mm per second. The larger 7 mm diameter Squiggle motor can push up to 500 grams but moves at slower speeds, about 2 mm per second. The Stall force for the standard SQ-100NM non-magnetic motor is more than 5 Newtons. If the load is distributed over several motors, more force could conceivably be achieved, as long as the load on each motor does not exceed its stall force. New Scale’s focus has been more on applications requiring very small motors, as opposed to those requiring very large forces. A 1.8 mm motor that can push more than 30 grams (0.3 Newtons) is a significant force in miniature motion systems, says Viggiano. Some Squiggle motors have been tested to more than 1-million cycles of continuous duty cycle. Failure comes from wearing of the screw threads, not fatigue of the crystals in the piezoelectrical material, says Viggiano. Squiggle motors are being used in MRI applications and are being designed into endoscopes and miniature microfluidic pumps. In the later cases, the precision and size of the motor is more important than its non-magnetic properties. In an MRI application, researchers at the Roswell Park Cancer Institute, Buffalo, N.Y., use Squiggle motors in studying the whole bodies of small animals. Researchers used a syringe pump driven by a Squiggle motor to inject contrast media into a live mouse in the MRI The Squiggle motor from New Scale Technologies is small enough to fit on the tip of a finger. 26 applianceDESIGN AD10084Exmek.indd 1 October 2008 8/26/08 3:39:02 PM www.applianceDESIGN.com http://www.exmek.com http://www.exmek.com http://www.applianceDESIGN.com

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Appliance Design - October 2008 Contents Editorial Shipments/Forecasts News Watch Prototyping - Materials Play the Part Prototyping - Mix & Match Motors Electronics Coatings Design Marts Association Report: AHRI Advertiser's Index

Appliance Design - October 2008

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