Developing and evaluating FlexiLayer fabrication technique for thin planar soft pneumatic robot with experimental demonstration

This thesis introduces FlexiLayer, a new fabrication technique for pneumatic thin planar soft actuators (PneuThin) that combines doctor blade coating and laser cutting. This method allows for precise control over layer thickness, cavity geometry, and material integration through a layer-by-layer construction process. The initial analysis of the finite element method (FEM) verified the conceptual design and identified key design parameters that affect actuator performance. The fabrication process achieved precise control of the thickness of the layer (coefficient of variation <4%) and precise cavity alignment (<1 mm deviation) using vacuum-assisted positioning.
Eight PneuThin configurations with varying three cavity shapes (rectangular, oval, triangular), cavity widths (5, 10 and 15 mm), and thickness distributions (0, 200 and 400 µm) were experimentally validated. The rectangular cavity design with a thickness difference of 400 µm achieved the highest bending (245 ± 33◦ at 5 psi) and the force output (265.6 ± 13.3 mN at 6.5 psi). Adding strain-limiting fabric layers improved control precision but reduced maximum bending by ≈ 63%. However, the configuration with strain limiting layers achieves an approximately ≈ 5% increase in force at 7 psi compared to the configuration without these layers at 6.5 psi. Two case studies demonstrated the applicability of the FlexiLayer method to robotic applications; a soft gripper capable of handling objects of 5-194 g and a quadrupedal robot achieving controlled locomotion at 1.7 ± 0.2 mm/s.
The refined FEM analysis, which incorporates experimentally characterised material properties, showed a strong correlation with the measured performance (R2 >0.96 for force prediction), establishing FEM as a reliable tool in the design process. The FlexiLayer technique overcomes limitations of traditional fabrication methods by offering improved precision, design flexibility, and material compatibility, while remaining simple and scalable. This research advances soft robotics fabrication by providing an approach to creating functional thin-planar soft robots with customisable properties.