Design and Development of a Button‐Style Transcutaneous Vagus Nerve Stimulation Device with Integrated PPG for HRV Monitoring†

Transcutaneous vagus nerve stimulation (tVNS) through auricular points emerges as a potential solution for mitigating depressive symptoms. This paper presents the development and evaluation of a button‐style transcutaneous auricular vagus nerve stimulation (taVNS) device for portable treatment and research applications. The device integrates photoplethysmography (PPG) for heart rate variability (HRV) monitoring, enabling real‐time evaluation of autonomic nervous system functionality. The system incorporates a user‐friendly design, including an Android application for monitoring HRV metrics and adjusting stimulation parameters, ensuring accessibility and personalization. In an initial evaluation involving nine volunteers, five participants demonstrated significant improvements in autonomic nervous system functionality, as evidenced by enhanced SDNN values, while four participants showed minimal response. These results confirmed the usability of the closed‐loop device and could potentially enhance future research efforts in personalized taVNS therapy.