Grant: Research Tools and Instruments

The instrument sought is a thermal imaging video camera. It will be used to capture the heating and cooling of polymer artificial muscles, among other applications. One of these artificial muscles consists of nylon fishing line that is twisted until it forms a helical coil. When heated and cooled it contracts and expands by a large amount. It typically changes length by 20 %, similar to our own muscle. And it can operate under about 100 times more force per area than our muscle. The combination of using low cost readily available materials, with the ability to perform a lot more work than our own muscle - for an equivalent weight and volume - makes these supercoiled nylon actuators attractive for use in medical devices, and as replacements for heavy solenoid valves in automobiles and plumbing, among other things. These threads can be woven into fabrics. Like muscle, they can be operated in parallel to produce graded forces, and to allow variable stiffness. However some aspects of the actuation of these materials are not well understood or need further development, and these are holding back more widespread application of the actuators. One is that the coiled threads stretch when load is increased. This one time stretch is reversible, so it disappears when the load is removed, but it makes it challenging to operate the actuator under conditions where load is changing - like when working against a spring, or picking and placing an object. We have some ideas on why this is happening, and will use a thermal video camera to understand this shape memory effect. We also want to increase speed of actuation. At the moment it typically takes a few seconds for the actuator to respond. The fastest large stroke response is about 5 Hz in filaments that are a quarter the diameter of a hair. How can we make this device faster, without overheating and damaging it? Again the thermal camera will help. Other applications will also use the thermal camera sought, including the development of fast micro actuators made from conducting polymers, production of smart sensing skins for robotic applications, identification of on chip heating, understanding the mechanics of ink deposition, observing sensory cell temperature recognition in vitro and more.