Improvement of Auricular Transcutaneous Vagal Closed-Loop Stimulation Device Regulated by Respiratory Signal

Transcutaneous auricular vagus nerve stimulation (tVNS) shows promising results in the treatment of chronic diseases, with similar efficacy to its invasive counterpart. Recent studies point to better efficiency in the therapy when synchronized with the respiratory cycle, specifically during the expiratory phase. However, existing portable systems do not allow the monitoring of respiratory parameters, being limited to generating pulses of adjustable intensity, but at a fixed frequency and without any monitoring measurements. In this context, a system is proposed, configured in a closed loop and integrated with sensors to acquire physiological data from users. The methodology uses NTC and MAX30102 sensors for respiratory and cardiac signals, respectively. Digital processing in embedded devices allows the detection of the expiratory phase of the respiratory cycle that is used for synchronization with the transcutaneous vagal stimulator. Finally, the assessment of the therapeutic effects of stimulation is performed instantaneously, calculated through quantitative methods of Heart Rate Variability (HRV), a method that is efficient for analyzing the autonomic regulation of vagal stimulation therapies, in clinical and outpatients. Thus, the applied feedback loop enables real-time biofeedback for tVNS synchronization, providing the necessary parameters for adaptive and personalized electrical stimulation, providing better clinical benefit. All the information extracted, after processing, allows the modulation of stimulation parameters in a closed-loop system, to provide users with potentially relevant therapy for different disorders and clinical applications.