Lithium ion batteries can be used for more efficient and larger shape changes than piezoelectrics.
Lithium ion batteries expand and contract under tremendous stresses, a must for devices that will be changing the shape of, say, a stiff helicopter rotor that's also exposed to aerodynamic forces. The electrically activated batteries can operate at low voltages (less than five volts) as compared to the hundreds of volts required by piezoelectrics. The materials that make up the batteries are also inherently light. The researchers have already demonstrated basic battery-based actuators that can pull and push with large force. Later this year, they hope to demonstrate the shape-morphing of a helicopter rotor blade. The morphing capability should allow for a more efficient design, ultimately making it possible for a vehicle to carry heavier loads. Team members say that other applications, including miniaturized devices for Micro-Electrical-Mechanical Systems (MEMS), may flow from these initial demonstrations.