Nexus: A Low-Cost Wearable AI Health Companion Using IoT, Edge AI and a Smartphone-Hosted Voice Assistant

Elderly people and patients with long-term conditions benefit from continuous, low-effort monitoring, yet most commercial health wearables are costly, screen-dependent and passive. This paper presents Nexus (Neural-Enabled eXtended User Support), a low-cost wearable AI health companion built on a three-layer IoT architecture. A wrist-worn ESP32-S3 device senses heart rate, blood oxygen saturation, motion and skin temperature and runs lightweight edge AI. A smartphone acts as the AI gateway and hosts speech recognition, a conversational assistant and speech synthesis. A caregiver interface provides status, alerts, history and location. The device has no display; it uses two-way voice, haptic feedback and a single SOS/TALK button. A proactive, health-focused assistant with short-term memory explains alerts in simple language, and a graded alert scheme with an emergency verification step reduces false alarms before caregivers are notified. The paper describes the requirements, hardware, software and AI design, privacy considerations, development methodology and a planned evaluation. Nexus is a health-monitoring and assistance prototype and is not a medical diagnostic device.