Electrical stimulation of the nervous system plays a crucial role in treating neurological diseases, sensory impairments, and movement disorders. However, conventional clinical approaches rely on the implantation of rigid metal electrodes, which can cause various issues such as low spatial resolution, poor selectivity, and long-term side effects. While recent advancements in nanoparticle systems that convert magnetic, optical, or mechanical energy into bioelectrical modulation have opened new avenues, challenges still remain. These include the need for genetic modification, diffusion of nanoparticles from the target site, and high-intensity thresholds to achieve effective neural stimulation at clinically relevant frequencies.

Our project introduces a novel wireless method for neural stimulation using piezoelectric magnetic Janus microparticles (PEMPs), which are designed to address these challenges. The microparticles, comparable in size to neural cells (20 μm in diameter), feature a unique dual-surface design. One side is conjugated with barium titanate nanoparticles for piezoelectric stimulation, while the other half is coated with a magnetically responsive material that allows precise orientation and movement using external magnetic fields. The functional design of PEMPs enables low-intensity focused ultrasound (LIFU) stimulation at high therapeutic frequencies (up to 200 Hz), while significantly lowering the intensity threshold for neural activation (<100 mW/cm^2).

In our in vitro experiments, PEMPs were shown to selectively target and stimulate dopaminergic neurons when modified with cell-selective antibodies. This capability is essential for cell-specific treatments in neurological disorders. Additionally, the orientation control provided by the magnetic coating ensures precise spatial and temporal neuromodulation, enhancing both the selectivity and efficacy of neural stimulation. This innovative PEMP design not only offers a solution to current limitations in particle-based neuromodulation systems but also holds potential for non-genetic, wireless neural stimulation techniques with broad implications for neurotherapeutic applications and basic neuroscience research.