Omnidirectional wireless power transfer via magnetoelectric composite transducer arrays for untethered bioelectronic systems

Angular or lateral misalignment remains a critical challenge in practical wireless power transfer (WPT) for bioelectronic systems, where the receiver (RX) continuously changes orientation relative to the transmitter (TX). Here, we report an omnidirectional magnetoelectric transducer array (OMETA) that enables compact, efficient, and misalignment-tolerant WPT using a triaxial configuration of orthogonally arranged laminated magnetoelectric (ME) composites. The orthogonal geometry ensures directional redundancy, maintaining stable voltage output regardless of RX orientation. With a total magnetoelectric composite transducer volume of only 6.6 mm³ (total receiver volume of 165 mm³), OMETA achieves superior output uniformity (V_max/V_min = 1.25) and delivers a peak voltage of 7.12 V under a 0.5 mT alternating magnetic field, surpassing state-of-the-art omnidirectional WPT devices that are orders of magnitude larger. Additionally, OMETA tolerates lateral misalignments up to 15 mm (around 2 body lengths) with minimal voltage degradation. Functional demonstrations include wireless powering of LED arrays and rapid charging of capacitors. As proof-of-concept applications, OMETA is integrated into a Venus flytrap enabled phytoactuator to provide electrical stimulation for biohybrid actuation. Moreover, OMETA serves as both a magnetic actuator and a wireless power source for the untethered capsule robot during gastrointestinal navigation. These results establish OMETA as a high-performance, miniaturized platform for alignment-independent wireless power transfer in next-generation untethered bioelectronic systems.