LOOP-IT FES

Galvanically ilsolated modules with different functionality:

EXG & DIO (8x EXG, 1x DIO)

• eight channel EXG (EEG, ECG, EMG) recording 
• digital triggering input & output  (DIO)
• towards personalised therapeutic brain-state dependent therapies in rehabilitation and psychiatry
• we provide a system enabling state-dependent and closed-loop controlled experiments in a stable time regimen with 1 - 3 ms turn-around time
  • data acquisition of ExG (EEG, ECG, EMG), 3-axis acceleration 24 bit / 1 kHz
  • data analysis of amplitude, frequency, latency, phase
  • modulation and control of the actuators tES / NMES / TMS
  • EEG / ECG / EMG biosignal acquisition (up to 1 ksps)
  • multichannel digital I/O interface (e. g. TMS, event-related potentials)
    
    

NIBS (2x tES)

• dual channel tES 
• temporal interference stimulation for enabling targeted structures deep inside the brain by steering the electric fields of maximum amplitude modulation
• features of the tES current source:
  • tDCS / tACS / tRNS waveforms
  • low 1/f noise,­ < 5 mA peak-to-peak, < 5 kHz bandwidth

NMES (2x NMES)

• dual channel NMES / FES
• voltage controlled REMOTE INPUT 
• features of the NMES / FES current source:
  • constant current source for generating short, steep current pulses or pulse trains, e. g. for experiments with charge-balanced symmetric or asymmetric currents
    • any sort of AC (or DC) current waveform possible (software-defined)
    • innovation: max. 200 mApp (up to 70 V), rise time < 2 μs
  • up to 300 kHz (3 dB)
  • isolated voltage output, proportional to the output current for monitoring purposes
• phase-dependent modulation of human corticospinal plasticity by associative pairing of transcranial and neuromuscular stimulation (tES & NMES)

Additional sensor interfaces for non-electrical biosignals

• e. g. movement, breathing, blood flow, temperature

Medical-grade hardware design

Standard interface and compact design

Direct access to hardware parameters via a supplied library (Python, RALGOL, C++)

• control a LOOP-IT FES device from a host PC, script it for real-time experiments, and monitor its output (LSL)
• LOOP-IT external interface  documentation
  
  

Integratable into BRAINSIGHT TMS  and ElevateTMS 

Conventional applications on TMS

• Collecting EMG for MEP investigations during TMS for read out on M1
• Collecting ECG for HR investigations during TMS for read out on DLPFC
• Collecting EEG for TEPP investigations during TMS for read out on the whole brain
  
  

Applications of brain-state depended on or closed-loop Stimulation

• Increasing corticospinal excitability by dynamically selecting stimulation phase and intensity based on the current brain state
  • Heiss C. et al. (2026). Closed-loop adaptation of transcranial magnetic stimulation intensity with electroencephalography feedback, Neuroimage
    
    

External Trigeminal Nerve Stimulation (eTNS)

• External trigeminal nerve stimulation (eTNS) is an emerging noninvasive neuromodulation technique that modulates brain network activity implicated in multiple neuropsychiatric disorders through the application of low-intensity electrical currents to the frontal branches of the trigeminal nerve 

Applications of combined transcranial and peripheral Stimulation 

• synchronized transcranial electrical (tACS) and peripheral neuromuscular stimulation
• FES/NMES synchronized tACS + FES/NMES under timing control. 
  • Tashiro et al. (2024). Synchronized application of closed-loop NMES and precision tACS in post-stroke hand rehabilitation,  Ther Adv Chronic Dis.

• EEG-timed NMES.  
  • Schütz S. & Gharabaghi A. (2026). EEG-timed neuromuscular stimulation shapes ipsilateral TMS-evoked motor responses in humans, Clinical Neurophysiology Practice
  • Askarikhomami S., Gharabaghi, A (2026) Phase-targeted peripheral stimulation modulates cortical sensorimotor responses, NeuroImage

Applications of temporal interference stimulation (TIF, tTIS)

• Temporal interference stimulation for enabling targeted structures deep inside the brain by steering the electric fields of maximum amplitude modulation
• LOOP-IT enables research-grade Temporal Interference Stimulation (tTIS) for non-invasive modulation of deep brain networks, supporting emerging applications in Parkinson's disease, memory, depression, epilepsy, motor control, and personalized neuromodulation. 
  
  • Grossman, N. et al. (2017). Noninvasive Deep Brain Stimulation via Temporally Interfering Electric Fields. Cell
  • Demchenko, I. et al. (2025). Human Applications of Transcranial Temporal Interference Stimulation: A Systematic Review. Brain Stimulation
  • Esmaeilpour, Z. et al. (2024). Temporal Interference Stimulation: Mechanisms, Modeling and Human Translation. Brain Stimul.
    
  • Missey, F. et al. (2025) Non-invasive temporal interference stimulation of the hippocampus suppresses epileptic biomarkers in patients with Epilepsy: biophysical differences between kilohertz and amplitude modulated stimulation, Brain Stimulation

Application on synchronised peripheral recording and tES

• Investigation on Tremor Detection and Phase-Synchronous Control of tES Current Sources. 
  
  • Fatemeh Sadeghi (2024). Multimodal Investigation of the Cerebello-thalamo-cortical Network in Parkinson’s Disease Tremor, Dissertation UKE
    
    

Applications in research in high-frequency electrical stimulation

• High-frequency alternating current (HFAC), or kilohertz-frequency stimulation, uses electrical signals in the 1-100 kHz range to alter neural activity without necessarily triggering action potentials. It can suppress, block, or modulate nerve function depending on the stimulation parameters and target tissue. In peripheral nerves, HFAC is best known for producing a rapid, reversible conduction block, making it a promising therapy for conditions such as chronic pain, spasticity, and bladder dysfunction. More recently, transcranial electrical and magnetic HFAC approaches have shown potential for non-invasive modulation of brain excitability and neural oscillations.

• References on transcranial stimulation
  • Negahbani E. et al. (2018). Targeting alpha-band oscillations in a cortical model with amplitude-modulated high-frequency transcranial electric stimulation. Neuroimage 
  • Labruna, L. et al. (2025). Kilohertz Transcranial Magnetic Perturbation (kTMP): A New Non-invasive Method to Modulate Cortical Excitability eLife
  • Reber, P. et al. (2026). Amplitude-modulated kilohertz stimulation targeting beta-band activity disrupts motor learning bioRxiv
    
    
• References on peripheral stimulation
  • Peña, E. et al. (2025). Ramped kilohertz-frequency signals produce nerve conduction block without onset response J. Neural Eng.
  • Opančar, A. et al. (2025). The same biophysical mechanism is involved in both temporal interference and direct kHz stimulation of peripheral nerves. Nat Commun 
    
    
    

Acoustoelectric neuromodulation

• By combining focused ultrasound and electrical stimulation to investigate localized electric field generation at the ultrasound focus. 
  • Rintoul, J. L. et al. (2026). Non-invasive in vivo acoustoelectric neuromodulation and its contribution to ultrasound stimulation. Nature Communications
    
    
    

Phrenic Nerve Stimulation

• Keogh, C. et al. (2022), Non-invasive phrenic nerve stimulation to avoid ventilator-induced diaphragm dysfunction in critical care. Artif Organs
• Wegert, L., et al. (2024). Activation thresholds for electrical phrenic nerve stimulation at the neck: evaluation of stimulation pulse parameters in a simulation study. Journal of Neural Engineering, 21(6)  Journal of Neural Engineering