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SMA Actuator Design

December 4, 2008

Preliminary prototype of a shape memory alloy actuated micropump.

Preliminary prototype of a shape memory alloy actuated micropump.


Here’s a link to a white paper I wrote describing some tips based on what I learned designing a shape memory alloy actuated micro-pump.

In 2004, I developed a micro-fluidic, “sip-and-spit” pump to move fluid within a hand-held device. I designed a pump instead of purchasing an off-the-shelf solution because I could not find an energy-efficient, low-cost actuator to satisfy the performance characteristics required. The pump is actuated using a pair of shape memory alloy (SMA) wires that contract when heated, driving the actuator back and forth per the micro-controller. I’d never worked with SMA’s before, and there was quite a learning curve to understand the both how the wire behaves and the conditions for failure.

A few years after the project ended, I published an article in Machine Design magazine describing everything I learned in the process. If you’re designing a similar SMA-based actuator, hopefully this information will save you a lot of frustration and development time. Having spent the time and effort to learn about these wires, I would happily use the wires again. Under the right conditions, they can be very robust, exceedingly inexpensive, and can be squeezed into a very small package.

SMA Actuator Design – A White Paper

Chad

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2 comments

  1. why use SMA and not a screw? I built one from a low cost scrrew table at http://www.macrondynamics.com and its pretty accurate


    • Thanks for the question. A screw-driven actuator would be a good choice if it met the accuracy, size, cost, and power requirements for a battery-powered handheld device. It looks like the Macron Dynamics screw-driven actuators are all capable of more than 6″ travel, so they’re not really suited for such an application. However, recently, I was working on a design with the Newscale Squiggle motor, a piezo-driven screw actuator, that would probably work well in this application. http://www.newscaletech.com/



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