Untethered ultrafast wall-climbing microbots

Fast climbing can significantly enhance the capabilities of microbots in applications such as environmental exploration and industrial transport. However, achieving fast and untethered wall-climbing microbots remains challenging due to the trade-offs between adhesion techniques, control strategies, and energy efficiency. Here, we propose a novel electrical control method for electroadhesion (EA) that enables ultrafast de-adhesion. By integrating a self-excited pulse module into the drive circuitry of the EA pads, this method effectively neutralizes the residual electric field, allowing the EA pads to achieve release speeds 90 to 177 times faster than conventional methods. Furthermore, it reduces adhesion force decay after reuse from 56% to 11%. Based on this approach, we developed an ultrafast microbot capable of vertical and inverted climbing, with a vertical velocity of 44.4 mm/s (0.45 body lengths per second) at a step frequency of 2.2 Hz, which is 5.6 to 25 times faster than robots employing conventional release methods. Additionally, we created the first untethered electroadhesive microbot by means of an efficient control strategy and an integrated high-voltage power system.