Design and Modelling of IPMC Kirigami

Abstract

Future consumer products, medical devices and manufacturing processes can benefit from systems with a high number and a high density of individually controlled actuators that are flexible and use little energy, materials and space. These systems with a high count and high density of actuators can be addressed as distributed actuation systems. In nature these distributed actuation systems are already present in the form of organs, eukaryotic cells or body parts such as an elephant’s trunk. This kind of system could be useful for handling fragile materials, delivering drugs inside the human body or creating replacement organs. Creating distributed mechatronic systems using conventional components is difficult, as the rigid parts often lead to complex constructions. This thesis presents a new paradigm for distributed actuation systems: combining planar bending smart materials with the Japanese art of Kirigami. This is demonstrated with the creation of a novel actuator design and modelling approach.First a literature study is presented on methods that have been used to actuate Origami and Kirigami (O&K) structures. General information is provided on several smart materials that can be used for this purpose. The reported methods and materials are evaluated on their potential for distributed actuation. The literature shows that electro-mechanical smart materials can be used for the design of distributed actuator systems. It is shown that multiple, scalable actuators can be designed in one sheet and can be actuated locally. Literature reveals preliminary research on cutting soft electro-active polymer (EAP) Kirigami structures. These EAPs are suitable for the creation of multi-DOF, distributed actuators using O&K techniques. However, this far the investigation addresses only cm-sized structures that exhibit a bending behaviour and the potential of the O&K techniques on EAPs have not been studied. The second study investigates the concept of utilizing Kirigami techniques on ionic polymer metal composite (IPMC) materials to manufacture distributed actuators. Different cm-sized designs are described and realized that produce a large strain linear motion from the bending motion of IPMCs. The designs are experimentally validated. The results demonstrate that it is possible to etch and cut a multitude of actuation units into planar bending smart material transducers and that bending actuation can be used to realize translation.To facilitate design and optimization of these IPMC Kirigami structures, a model is needed that predicts the electro-mechanical behaviour and is easy to implement. Existing models are not suitable as they will result in complex and elaborate model constructions when more advanced structures have to be implemented. This thesis presents a practical electrical model in Comsol Multiphysics. The electrical parameters of an IPMC beam are identified. Identified properties include the surface conductivity, through material conductivity and permittivity. The electrical models are validated by comparing the simulations with a time-domain experiment with a sinusoidal input signal of 1V at 1Hz. The results show that the models can be used to describe the macroscopic electrical behavior and can be further used in analysing more complex structures ones the mechanical part of the Comsol model is also completed.