In the rapidly evolving field of neuromodulation, a groundbreaking advancement has emerged with the design, construction, and deployment of a multi-locus transcranial magnetic stimulation (mTMS) system tailored for clinical use. This state-of-the-art technology represents a significant leap forward in noninvasive brain stimulation by integrating a sophisticated array of overlapping coils that enable precise targeting of multiple cortical regions without the need for physical repositioning. Such innovation holds immense potential for both research and treatment of neurological disorders, promising enhanced flexibility and accuracy in brain stimulation protocols.
At the heart of this new mTMS system lies an intricate architecture governed by a field-programmable gate array (FPGA), which orchestrates the synchronization and control of five distinct stimulation channels. Each channel is individually powered by a dedicated high-voltage capacitor linked to a pulse circuit, enabling independent and simultaneous delivery of electromagnetic stimuli across the coil array. This modular design not only amplifies functional versatility but also enhances the reliability and safety profile of the entire apparatus, essential for clinical environments.
The engineering behind the coil array is as critical as its electronic control. The five coils are strategically designed to overlap in such a way that the system can dynamically steer the induced magnetic fields to distinct cortical targets. This eliminates the conventional constraints imposed by mechanical coil movement, which are often cumbersome, time-consuming, and introduce variability in stimulation placement. By leveraging electromagnetic superposition principles, the device can sculpt the magnetic field landscape with high spatial resolution, paving the way for new therapeutic paradigms.
Safety considerations were paramount during the development process, prompting the incorporation of redundancy both in hardware components and embedded firmware. Custom-designed circuit boards monitor system status in real-time, automatically detecting and reporting errors to prevent malfunction or unintended stimulation. Such fail-safe mechanisms are vital for patient protection and have been rigorously tested to meet the stringent standards required for hospital use. This robust architecture ensures that the system maintains performance integrity even under complex operational scenarios.
A pivotal aspect of validating the mTMS device involved conducting automated motor mapping tests, which served as experimental confirmation of the system’s electronic targeting precision. Through the stimulation of motor cortical areas in volunteer subjects, researchers demonstrated that the device could reliably evoke motor responses corresponding to targeted brain regions without manual coil adjustments. This finding underscores the transformative potential of mTMS for diagnostic and research applications, particularly in neurorehabilitation and functional brain mapping.
Deployment of the system at the Hertie Institute for Clinical Brain Research in Tübingen, Germany, marks an important milestone, signifying readiness for clinical trials and future therapeutic applications. This transition from prototype to clinical-grade apparatus reflects substantial improvements over previous designs, particularly in enhancing user safety and ease of operation. The successful integration into a hospital setting lays the groundwork for broader adoption and paves the way for clinical protocols utilizing multi-locus stimulation.
From a technical perspective, the novel use of an FPGA as the command center offers unparalleled flexibility in programming pulse sequences and adapting stimulation parameters in real time. Unlike conventional microcontroller-based setups, the FPGA handles parallel operations efficiently, enabling simultaneous control of all five coils. This capability could allow for complex stimulation patterns hitherto impossible with single-coil systems, giving clinicians fine-grained control over therapeutic modulation.
The introduction of this multi-coil array system also represents a strategic departure from existing TMS technology, which predominantly relies on moving a single coil across the scalp to stimulate different brain regions. By obviating the need for physical repositioning, the new system reduces procedure duration and operator burden, thereby enhancing patient comfort and clinical throughput. This innovation may also improve repeatability and reproducibility of stimulation protocols, crucial factors in both research and therapy.
Moreover, the device’s architecture incorporates real-time monitoring of both hardware status and environmental conditions to enhance safety. Sensors integrated across the system detect overheating, excessive current flow, or coil faults, initiating immediate shutdown if thresholds are breached. Such proactive safety features are indispensable for clinical deployment and instill confidence among both clinicians and patients regarding the device’s operational reliability.
Looking ahead, this advancement could revolutionize neuromodulation techniques for a wide spectrum of neurological and psychiatric disorders. The capacity to stimulate multiple cortical sites with millisecond precision and flexible spatial control opens new avenues for tailored treatments in conditions such as depression, epilepsy, and stroke rehabilitation. Furthermore, the system’s programmability offers researchers a powerful tool for probing the complex dynamics of brain networks and their role in health and disease.
In conclusion, the successful creation and clinical deployment of a multi-locus transcranial magnetic stimulation device represent a milestone in biomedical engineering and neuroscience. By marrying innovation in hardware design with sophisticated electronic control and robust safety features, the authors have translated a concept previously confined to laboratories into a practical clinical solution. As this technology gains traction, it is poised to make a lasting impact on neuromodulation therapies and brain research worldwide.
Subject of Research: Multi-locus transcranial magnetic stimulation system development for clinical applications
Article Title: Design, construction, and deployment of a multi-locus transcranial magnetic stimulation system for clinical use
Article References:
Sinisalo, H., Kahilakoski, OP., Souza, V.H. et al. Design, construction, and deployment of a multi-locus transcranial magnetic stimulation system for clinical use. BioMed Eng OnLine 24, 61 (2025). https://doi.org/10.1186/s12938-025-01393-6
Image Credits: AI Generated
DOI: https://doi.org/10.1186/s12938-025-01393-6
