Gear system will assemble by itself

A technique created by Engineers at Columbia University to utilize


thermal expansion characteristics of dissimilar materials to create


mechanical devices could prove very useful in building small-scale


machines. A thin metal film is deposited on to a special polymer. When


the temperature is reduced, wrinkles form in the composite material


based on the structure's design due to the differing thermal expansion


characteristics of the materials. These wrinkles can be made to produce


formations such as gear teeth and other mechanical components. After


the required pattern is obtained, a hardening process is used to fix


the device's shape permanently. The application for micro and


nano-scale machines is more efficient because of its simplicity and


low production cost.