Objective Sympathetic Neural State Monitoring Via Soft, Wireless Bioelectronics

Individuals with dementia, severe post-traumatic stress disorder, and serious mental illness experience rapid and often subtle shifts in emotional state, yet caregivers currently lack objective tools to monitor these changes in real time. Existing neuroimaging and electrophysiologic approaches offer high accuracy but are impractical for continuous, everyday use, while conventional peripheral biomarkers such as galvanic skin response and heart rate variability suffer from substantial confounding influences and calibration challenges. Cardio‑mechanical signals, particularly the seismocardiogram (SCG), offer a promising alternative because sympathetic activation and stress hormones directly modulate cardiac mechanics. Here, we introduce a soft, wireless, skin‑conformal sternal patch that captures high‑fidelity SCG signals and broadcast via Bluetooth to a receiver in real time. The device is carefully designed to closely match the mechanical properties of skin and preserve vibration transmission. In a preliminary human subjects study using alternating relaxed and emotionally engaged video stimuli, principal component analysis of the extracted features revealed distinct clustering between relaxed and engaged states, driven predominantly by amplitude differentials in mitral‑associated SCG features. These early results suggest that soft sternal SCG patches may enable practical, objective monitoring of emotional changes in those with dementia, PTSD, and severe mental illness.