A Reusable Non-Adhesive Chest-Wall Acoustic Wearable Estimates Respiratory Rate During Rest and Exercise

Respiratory rate is a clinically and behaviourally informative signal, yet continuous monitoring outside quiet rest remains difficult. Wearable systems often infer breathing indirectly from cardiovascular or motion surrogates, while direct chest-wall sensing has typically depended on skin adhesion or controlled laboratory conditions. We evaluated Alveos One, a body-coupled acoustic and inertial chest-wall wearable, to test whether a reusable magnet-through-textile form factor can estimate respiratory rate across rest, controlled breathing, motion tasks, and graded exercise. In a single-session protocol, we analysed recordings from 20 healthy adults referenced to structured light plethysmography, breath-by-breath spirometry, and paced-breathing targets. Estimates fell within 2 breaths/min of the reference for 94.6% of valid windows during rest and controlled breathing and 79.3% during exercise; Bland-Altman bias was - 0.24 breaths/min during rest and controlled breathing and -1.07 breaths/min during exercise. Secondary analyses compared the magnet configuration with a skin-adhered patch and assessed airway-mode classification and motion-related operating limits. These findings support reusable, non-adhesive chest-wall acoustic sensing as a practical route to longitudinal respiratory-rate monitoring, and identify rising motion intensity and high ventilatory demand as the principal limits on confident reporting.