IONIC POLYMER-METAL COMPOSITE ARTIFICIAL MUSCLES AND SENSORS: A CONTROL SYSTEMS PERSPECTIVE By

IONIC POLYMER-METAL COMPOSITE ARTIFICIAL MUSCLES AND SENSORS: A CONTROL SYSTEMS PERSPECTIVE By Zheng Chen Ionic polymer metal composites (IPMCs) form an important category of electroactive polymers (EAPs), also known as artificial muscles. IPMCs have many potential applications in robotics, biomedical devices, and micro/nano manipulation systems. In this dissertation, a systems perspective is taken to explore the potential of these novel materials in smart microsystems. In particular, this investigation includes modeling, control, compact sensing, and microfabrication techniques for IPMCs. The starting point of this research is control-oriented modeling of IPMC sensors and actuators for obtaining faithful and practical mathematical models. The models are derived by exactly solving the governing partial differential equation in the Laplace domain with the consideration of distributed surface resistance. They are represented by infinitedimensional transfer functions in terms of physical parameters and dimensions, which are scalable and amenable to model reduction. The actuation model of IPMC has been applied to develop a model for biomimetic robotic fish propelled by an IPMC actuator, which is useful in optimal design and control of the robotic fish. A nonlinear control-oriented model for IPMC has also been investigated to accommodate large deformation of IPMC under a relatively high voltage input. Feedback control of IPMC actuators is often necessary in bio and micro applications. Since traditional sensors cannot be embedded into micro/bio systems, the second aspect of this research is to develop a compact sensing scheme for IPMC actuators. An integrated sensory actuator, IPMC/PVDF hybrid structure, utilizes an IPMC as actuator and one or two polyvinylidene fluoride (PVDF) films as sensors to implement simultaneous actuation and sensing. An IPMC/PVDF single-mode structure has been tested in open-loop microinjection of fruit-fly embryos. Feedback control of IPMC with integrated differential-mode sensors has been implemented in real-time, which shows accuracy and robustness of this sensory actuator. Since microfabrication of IPMC is another challenge in realizing smart microsystems enabled by IPMCs, the third aspect of this research is to develop microfabrication techniques for IPMC. A monolithic microfabrication process for IPMC actuators capable of complex deformation has been developed. Two novel fabrication techniques have been introduced: 1) selectively thinning down Nafion with plasma etch, to make the passive areas thin and compliant; 2) impregnating Nafion film with platinum ions before the patterning step, which significantly increases the film stiffness and allows subsequent lithography and other steps. As the first application, an artificial pectoral fin has been fabricated using the developed process flow. It can generate bending, twisting, and cupping motions, which shows promise in robotic fish applications. Copyright by Zheng Chen 2009 DEDICATION To Mom, Dad, and Wife