Miniaturized wireless bioelectronics for electrically driven biohybrid robots

Although biohybrid robots offer the potential for soft, adaptive actuation by harnessing living muscle, practical operation in cell culture environments is often limited by the requirement of immersed leads or cumbersome stimulation equipment. Here, we present a thin, miniaturized, wireless bioelectronic stimulator that can electrically drive biohybrid robots while maintaining stability in aqueous cell culture media. Built on a 50-µm liquid crystal polymer (LCP) substrate, the device integrates a planar receiving coil, interconnects, a diode-based rectifier, and a tank capacitor. This enables the device to convert an approximately 4.9-MHz radio-frequency (RF) input into pulsed direct current (DC), which is delivered through integrated stimulation electrodes. The stimulator has a footprint of ~ 32 mm² and a total thickness and mass of ~ 100 μm and ~ 7 mg, respectively. We integrated the stimulator with a nanopatterned carbon nanotube (CNT)/gelatin hydrogel fin seeded with human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) to generate propulsion through fin flapping. By optimizing the thickness of the polydimethylsiloxane (PDMS) encapsulation layer, the density was tuned, and the robot remained freely floating and retained shape integrity during operation. This produced autonomous forward locomotion of 74.8 ± 16.4 μm s^- 1. The stimulator generated distance-dependent output voltage pulses and enabled external pacing/modulation under the tested conditions, without a marked loss of cardiomyocyte attachment or α-actinin-positive sarcomeric organization. Together, these results provide a proof-of-concept compact, media-compatible, wireless bioelectronic interface toward closed-system biohybrid robotics.