Shape Memory metals were developed by NASA for the space industry, and have been used for increasing applications down on earth. For example,there have been limited studies on using these materials in robotics. They make it possible to create very light robots.
The Dash4 memory metal actuator provides a stroke of 0.23" and over 1.75 pounds of actuation force. The built-in limit switch allows for safe operation over a wide range of voltage (thus, actuation speed) when used along with the MAD-v5 (sold separately). The Dash4 is just under an inch wide, and less than 0.1" thick!