Miniature High Force, Long Stroke Linear Shape Memory Alloy Actuators

Shape Memory Alloys (SMAs) are metal alloys (of Nickel-Titanium, for example) that can change their shape when heated. When drawn and processed in wire form, the shape change is an aggressive contraction, with useable lifetimes of millions of cycles. Despite this fact, SMAs have largely been a scientific curiosity, finding very little commercial use as actuators since their discovery over 30 years ago. The apparent lack of practical application may be attributable to their low recoverable strain (~4% of total wire length). MIGA Motor Company has numerous international patents covering Displacement Multiplication (DM) techniques that allow us to package large strokes in highly compact, lightweight packages. Our current commercially available electric linear actuators provide 1/2" of stroke with 4.5 pounds of output force. We propose to develop several high force variants of our DM designs, allowing up to 32 lbf (high cycle count) or 48 lbf (hundreds of cycles) in a device weighing less than 2 ounces. The manufacturing techniques that we have developed in manufacturing the DM actuators have paved the way to expansion into the high force realm: high reliability wire attachment methods, use of high temperature thermoplastics, protected or over-molded precision chemically-etched stainless-steel stages, and various load-sharing techniques have enabled these powerful actuators to finally become a reality.