Wearable Sensor System for Diver Vital Sign Monitoring

Area of Science:

• Biomedical Engineering
• Physiological Monitoring
• Underwater Technology

Background:

• Military divers face physiological limits, with hypoxia and reduced cardiac output posing risks of unconsciousness and death.
• Current underwater safety systems offer limited vital sign monitoring capabilities.
• Conventional pulse oximetry (PO) and photoplethysmography (PPG) devices are unreliable under diving conditions (motion, immersion, communication constraints).

Purpose of the Study:

• To develop a wearable network, HYDROS (HYbrid Diver Remote Observation System), for continuous underwater physiological monitoring and data transmission.
• To address the limitations of existing systems in monitoring military divers' vital signs during operations.

Main Methods:

• HYDROS integrates a multi-wavelength PPG sensor, inertial sensors, processing unit, and ultrasonic transducer for underwater communication.
• Motion-tolerant Bayesian algorithms estimate heart rate (HR) and oxygen saturation (SpO2).
• Frequency-multiplexed acoustic signaling enables simultaneous data transmission from multiple divers.

Main Results:

• HYDROS SpO2 closely matched arterial blood gas SaO2 (2.71% RMSE).
• Accurate HR and SpO2 readings were maintained during movement and simulated hypoxia.
• Acoustic transmission achieved over 90% packet fidelity up to 300 ft, supporting multi-diver communication.
• The system functioned reliably during dives to 130 ft without degradation.

Conclusions:

• HYDROS is the first integrated, noninvasive underwater physiological monitoring system using motion-tolerant PPG and acoustic transmission.
• The system enables real-time diver health monitoring and early hypoxia detection.
• HYDROS enhances operational safety and medical readiness for military diving.