Insect-scale aerial vehicles are useful tools for communication, environmental sensing and surveying confined spaces. However, the lack of lightweight high-power-density batteries has limited the untethered flight durations of these micro aerial vehicles. Wireless power transmission using radiofrequency electromagnetic waves could potentially offer transmissivity through obstacles, wave-targeting/focusing capabilities and non-mechanical steering of the vehicles via phased-array antennas. But the use of radiofrequency power transmission has so far been limited to larger vehicles. Here we show that a wireless radiofrequency power supply can be used to drive an insect-scale flapping-wing aerial vehicle. We use a sub-gram radiofrequency power receiver with a power-to-weight density of 4,900 W kg^–1, which is five times higher than that of off-the-shelf lithium polymer batteries of similar mass. With this system, we demonstrate the untethered take off of the flapping-wing micro aerial vehicle. Our RF-powered aircraft has a mass of 1.8 g and is more than 25 times lighter than previous radiofrequency-powered micro aerial vehicles.

In this letter, we present the design and the performance of a prototype bioinspired flapping-wing micro aerial vehicle with piezoelectric direct-driven actuation. This type of actuation is superior in terms of structural simplicity because it does not include any transmission mechanism. Instead, a unimorph piezoelectric actuator directly drives the wing. We designed and fabricated a two-wing prototype with a wingspan of 114 mm and successfully demonstrated takeoff using an external power source under a one-degree-of-freedom constraint. The total mass of the prototype was 598 mg, and the maximum measured lift force was 6.52 mN (665 mgf) at a driving voltage of 100 V. We achieved tethered flight using the proposed direct-driven piezoelectric actuator considering the constraint.

Insect-scale micro-aerial vehicles (MAV) are becoming increasingly important for sensing and mapping spatially constrained environments. However, achieving untethered flight powered by a small and lightweight on-board energy source remains a challenge. In this study, we successfully demonstrated the untethered takeoff of a flapping-wing MAV powered by a commercially available LiPo battery for a short duration without stability control. By incorporating a high-efficiency direct-drive piezoelectric actuator, and an optimized control circuit for high-impedance-width modulation and charge recovery, this electronics configuration realizes over 5 min of practical operation with a thrust of 1.5 times its own weight, while offering wireless communication capability and sensors for attitude estimation. Our MAV has a total mass of 2.1 g, which is an eight-fold reduction compared to the lightest battery-powered tailless flapping-wing MAV currently available, making this the first report of a battery-powered tailless flapping-wing MAV with insect-scale weight.

We propose a network architecture for electronic skin with an extensive sensor array—crucial for enabling robots to perceive their environment and interact effectively with humans. Fault tolerance is essential for electronic skins on robot exteriors. Although self-healing electronic skins targeting minor damages are studied using material-based approaches, substantial damages such as severe cuts necessitate re-establishing communication pathways, traditionally performed with high-functionality microprocessor sensor nodes. However, this method is costly, increases latency, and boosts power usage, limiting scalability for large, nuanced sensation-mimicking sensor arrays. Our proposed system features sensor nodes consisting of only a few dozen logic circuits, enabling them to autonomously reconstruct reading pathways. These nodes can adapt to topological changes within the sensor network caused by disconnections and reconnections. Testing confirms rapid reading times of only a few microseconds and power consumption of 1.88 μW/node at a 1 kHz sampling rate. This advancement significantly boosts robots’ collaborative potential with humans.

We present an analytical model of a flapping-wing actuator, including its electrical, aerodynamic, and mechanical systems, for estimating the lift force from the input electrical power. The actuator is modeled as a two-degree-of-freedom kinematic system with semi-empirical quasi-steady aerodynamic forces and the electromechanical effect of piezoelectricity. We fabricated actuators of two different scales with wing lengths of 17.0 and 32.4 mm and measured their performances in terms of the stroke/pitching angle, average lift force, and average consumed power. The experimental results were in good agreement with the analytical calculation for both types of actuators; the errors in the evaluated characteristics were less than 30%. The results indicated that the analytical model well simulates the actual prototypes.

We present a prototype flapping-wing actuator with a direct-driven mechanism to generate lift in micro- and nano-aerial vehicles. This mechanism has an advantage of simplicity because it has no transmission system between the actuator and wing. We fabricated the piezoelectric unimorph actuator from single-crystal PIN-PMN-PT, which achieved a lift force up to 1.45 mN, a value about 1.9 times larger than the mass of the actuator itself. This is the first reported demonstration of an insect-scale actuator with a direct-driven mechanism that can generate a lift force greater than its own weight.