Fleas in nature generally have potent muscles for jumping and crawling abilities to overcome obstacles in complex environments, while it is challenging for flea-sized robots to have powerful actuators due to the size effect. This work presents a novel high-voltage pulsed actuator for a flea-sized robot (3.4mm-in-length) to achieve powerful jumping and fast crawling locomotion. The working principle of the actuator is based on the electric arcing phenomenon between two electrodes under high-voltage pulses. The jumping height and length of the 3.4mm flea-sized robot can be up to 46 and 87 times of body lengths, respectively, and the crawling speed can be over 46 body lengths per second on a flat surface. With its tiny size and high jumping performance, the flea-sized robot can jump over obstacles and then crawl through narrow gaps. This work presents the world's first robot with the same body size and locomotor performance as fleas in nature, significantly expanding the use scenario of microrobots.

The ability to move backward is crucial for millimeter-scale microrobots to navigate dead-end tunnels that are too narrow to allow for turning maneuvers. In this study, we introduce a 15-mm-long legged microrobot, BHMbot-B, which is capable of rapid forward and backward locomotion through vibration mode transition control. By properly arranging the vibratory motions of the magnet, cantilever, and linkages, the pitching movement of the body and the vibration of the forelegs are in phase during the first-order vibration mode of the cantilever and in antiphase during the second-order mode, which induces the forward and backward movement of the microrobot. Owing to its outstanding load-bearing capacity, the BHMbot-B equipped with dual electromagnetic actuators, an onboard battery, and a control circuit, can execute complex running trajectories under wireless command. Its maximum untethered running speeds are evaluated as 18.0 BL/s (360 mm/s) in the forward direction and 16.9 BL/s (338 mm/s) in the backward direction.

Stimulated by an electric field, the plasmonic thermal energy can be applied to drive a millimetre-sized actuator, showing promising applications.

It is challenging for microrobots to fly using onboard energy due to the relatively heavy power supplies and inefficient actuators that are limited to a small size (mass less than 1000 mg and wingspan less than 100 mm). Inspired by the movement of jellyfish in nature (Physophora hydrostatica), herein, a microscale aerial vehicle FlyJelly is introduced, powered by onboard energy to achieve untethered flight. FlyJelly uses a balloon filled with helium to overcome self‐gravity and an actuator powered by electrostatic power to generate thrust. The balloon, heat sealed with two gold‐covered Mylar films, weighs 95.56 mg, provides 257.9 mg of buoyancy when filled with helium, and stores 19.457 × 10⁻³ J of energy when powered by 2400 V of direct current. The electrostatic actuator is composed of multiflapping units arranged radially and symmetrically, consuming only 0.3370 mW of power but generating a thrust of 0.2271 mN to drive the vehicle for flight. Benefiting from a design of distributed propulsion, FlyJelly is highly reliable and continues to work well even after the actuator is damaged. The milligram‐level weight, untethered flight with onboard energy, and high reliability make the prototype suitable for development as a long‐term remote exploration and search‐and‐rescue mission.

Several microrobots driven by capacitive actuators have shown excellent performance because of the high power density and low working current of the actuators. However, these capacitive actuators need high alternating working voltage (hundreds or thousands of volts), which results in heavy and bulky inverter circuits and increases the difficulty of achieving untethered movements for microrobots. In this work, we report a novel and lightweight mechanical electrostatic inverter based on the self-excited electrostatic vibration for untethered crawling microrobots driven by piezoelectric actuators (working under 300 volts) and dielectric elastomer actuators (working under 3600 volts), respectively. The electrostatic inverter, consisting of just two electrodes and a conductive cantilever, is integrated into the body of the microrobots to generate a high alternating voltage from 200 to 10000 volts, and its weight is in milligram scale (16.2 mg - 96.7 mg). Powered by onboard capacitors, two untethered microrobots worked continuously for 3 s - 6 s and moved at a maximum speed of 18 - 41 mm/s. The work provides another scheme for designing untethered microrobots driven by capacitive actuators with high working voltage up to thousands of volts.

It is a significant challenge for microrobots to achieve fast crawling speed at the millimeter scale due to the limitation of actuator size effects. In this letter, we have designed a millimeter-scale microrobot configuration based on a new electric pulse drive principle. The microrobot has a high resonant frequency by utilizing Joual Heat generated from the pulsed electric arc. This vibrational excitation causes friction between the robot's legs and the ground to drive a fast-crawling movement. The microrobot can crawl forward on a smooth glass surface at a speed of up to 66.3 body lengths per second. It is also possible to move forward on a rough sandpaper surface at the maximum speed of up to 39.3 body lengths per second. The robot's millimeter size, fast crawling speed, and environmental adaptability enable it to operate in a wide range of future detection and reconnaissance applications.