A Statistical Approach to Assess the Relationship Between Interdigitated Geometry Characteristics and Shear Stress Performance in Electro-Adhesive Devices

Over the past decade, several studies have proposed optimization strategies targeting components of Electro-Adhesive Devices (EAD) to enhance their performance in terms of normal or shear grasping force. Notably, the comb-shaped interdigitated geometry, widely used in EAD grasping applications, has demonstrated superior shear force performance. While many studies have focused on determining the optimal electrode geometry for specific applications, employing analytical models and finite element method (FEM) simulations of electrostatic interdigitated systems, few studies have systematically explored the optimal combination of electrode gap and width, incorporating an empirical evaluation. However, the EAD performance is often influenced by several physical factors related to the manufacturing process and environmental conditions, which are neglected by analytical and numerical models. This work presents an empirical-statistical method for optimizing EADs through a study based on the Design of Experiments (DoE) technique. EADs comprising two comb-shaped electrodes are fabricated using the Drop on Demand inkjet printing technique to deposit a silver-based ink on thin polyethylene terephthalate (PET) film. By varying the gap and width, and by assessing shear force through shear stress tests, the best combination for grasping a given material is determined, providing a suitable benchmark for selecting the appropriate device geometry for a specific application. Tests on a conductive substrate resulted in less intense electro-adhesive phenomena than tests on a dielectric substrate. In both cases, increasing the electrode gap decreased the shear stress. However, reducing electrode width led to opposite effects: shear stress increased on the dielectric substrate, but decreased on the conductive one.