Multifunctional auricular vagus nerve stimulator for closed-loop application

Abstract

Auricular vagus nerve stimulation (aVNS) is a novel neuromodulatory therapy used in the treatment of various types of chronic systemic disorders. Currently, aVNS is non-individualized, disregarding the personal state of the patient and therefore making it difficult to reach optimum therapeutic outcomes. A closed-loop aVNS system is required to avoid overstimulation and under-stimulation of patients, leading to improved outcomes. This can be achieved by monitoring physiological parameters and adjusting aVNS parameters according to the individual physiological data. We developed a novel aVNS hardware for closed-loop applications, which utilizes diverse physiological sensing using external sensors and/or embedded sensors, processes and analyzes the acquired data in real-time and can directly govern the stimulation parameters. In a first experiment, it was shown that aVNS stimulation synchronized with electrocardiography and photo plethysmography while mimicking baroreceptor-related afferent input along the afferent vagus nerve into the brain can be successfully applied. The designed system identified >90% of the cardiac cycles and activated stimulation at the target point with ± 100ms precision despite heart rate variability. The developed system offers a solid basis for future research into personalization of aVNS.