Electroadhesive Pad Design for Increased Adhesion of Climbing Microrobots on Diverse Terrains

While previous studies have explored electroadhesive climbing using the insect-scale Harvard Ambulatory Microrobot platform, the robot's ability to climb reliably over irregular terrain has remained limited. To evaluate potential solutions, we conducted an investigation of the electroadhesive pad design space and characterized the shear force climbing capabilities of the robot with different pad designs. We find that on smooth, flat terrains, a large simple circular footpad structure exhibited the greatest shear forces. However, on rougher inclined surfaces, pads which adjusted the width, length, and number of spoke-like features provide greater compliance and achieve more consistent shear adhesion forces. Such compliant spoke pad designs on rough surfaces performed with 84 % stick reliability and 1.02 kPa average adhesion forces compared to 45 % stick reliability and 0.81 kPa average adhesion forces for a comparable circular pad. We demonstrate the improved climbing capability of the 4.5 cm robot on terrain with 75 $\mu$m roughness and observe an average increase in climbing speed of 48 % over a range of angles from 0–45 degrees.