Quantized Wireless Vagus Nerve Stimulation via Magnetoelectric Effect in Composite PLLA/Fe ₂ O ₃ ‐Nanorod Microparticles

Peripheral nerve stimulation is a promising non‐pharmacological therapy for conditions ranging from epilepsy to metabolic disorders. However, a critical technological gap exists between invasive implants and non‐specific transcutaneous systems. Here, a minimally invasive and targeted alternative is introduced using standardized, cell‐sized cylindrical microactuators. These microparticles are composed of crystallized poly(L‐lactic acid) (PLLA) embedding aligned magnetostrictive iron oxide nanorods (NRs). This unique design enables a stimulation paradigm where each individual PLLA/NR microparticle (PLLA/NR‐MP) serves as a discrete wireless excitation unit, permitting localized modulation while mitigating excitotoxicity. In vitro, individual PLLA/NR‐MPs reliably trigger calcium influx in mouse hippocampal neurons. Furthermore, in vivo experiments demonstrate frequency‐ and threshold‐dependent modulation of vagus nerve activity, governed by the effective number of engaged microactuators alongside the amplitudes of the applied constant and alternating magnetic fields. Specifically, magnetoelectric stimulation via a PLLA/NR‐MP matrix implanted around the mouse vagus nerve leads to an increased respiratory rate and a decreased heart rate once the activation threshold is exceeded. This work establishes a wireless platform based on biocompatible active components for the modulation of organ‐level functions, presenting a promising strategy for future neuromodulation in neurological and metabolic disorders.