Design, fabrication, and characterization of controllable conducting polymer actuation systems

Abstract

The geometric, hierarchal, multifunctional composition of mammalian skeletal muscle and the neuromuscular system consists of actuation elements, length sensors, force sensors, localized energy storage, controlled energy delivery, computational components, and intercommunication pathways. Conducting polymer materials are versatile enough to perform all of the above functions. This work explores the design, characterization, and implementation of three conducting polymer components in building artificial muscle actuation systems: actuators, length sensors, and energy storage. The first systematic strain characterization of polypyrrole actuators at voltages above 1 V for a frequency range of 0.01 Hz to 100 Hz is reported. Material, mechanical, and electrical properties of polypyrrole length sensors are evaluated over the same frequency range. Polypyrrole supercapacitors are evaluated as a function of dopant, electrolyte, geometry, and mass, enabling the determination of their capacitance, charge-discharge lifetime, and self-discharge. Fabrication techniques for combining multiple conducting polymer components (actuators, length sensors, and energy storage elements) by means of electrically insulated, mechanical attachments are developed and demonstrated. An all-polymer, open loop linear contractile actuation system is presented, along with the first conducting polymer powered conducting polymer actuators, and the first tripolymer system. These results build a foundation upon which large, scalable, self-powered, all polymer electro-chemo-mechanical actuation systems can be developed for a future set of conducting polymer artificial muscle systems.