A Flight-Helmet Compatible Closed-loop Electrooculography and Vagal Nerve Stimulation Device for Fatigue Mitigation...

Modern military aircraft make high perceptual and cognitive demands of users, taxing the limits of human capabilities. When complicated by fatigue and stress, this can lead to poor mission outcomes or even potentially fatal accidents. The high risk of human error caused by fatigue-related cognitive impairment continues to be one of the most challenging problems facing the military. Neuromodulation has emerged as a promising nonpharmacologic mitigation strategy but requires continuous monitoring of the operator state. Although military aircraft have hundreds of sensors, their operators' vital signs and cognitive states are not often monitored. There is thus a dire need to monitor fatigue in pilots in order to enable real-time mitigation. Quantum Applied Science and Research (QUASAR) and Soterix Medical Inc. have integrated wearable electrooculography (EOG) sensors with non-invasive neurostimulation to address this need and offer a viable closed-loop fatigue detection and mitigation solution that could reduce the rate of mishaps and improve operational efficiency. Here, we report on embedding these sensors into a headband, called GOE-Stim, that can be worn with or without an avionics helmet as a proof-of-concept of the ability to monitor pilot fatigue levels and deliver closed-loop neurostimulation to mitigate fatigue during flight.

A functional prototype of the GOE-Stim headband was designed to ensure compatibility with flight helmets, comfort, and adherence to aerospace safety standards. The GOE-Stim headband features a flexible silicone rubber band with a rigid outer structure, ensuring comfort, sensor stability, and flight helmet compatibility. The device integrates EOG sensors at locations optimized for high-fidelity signal acquisition, supported by a robust electronics system for data processing, wireless communication, and Transcutaneous vagus nerve stimulation (tVNS) delivery. Ground and flight testing at Embry-Riddle Aeronautical University evaluated electromagnetic compatibility, Global Positioning System (GPS) interference, and operational reliability, including in-flight performance. Testing at QUASAR included a spatial cueing task and a computer-based resource management task to evaluate the device's sensitivity to saccadic eye movements and ability to collect stable, high-quality EOG signals.

The GOE-Stim headband underwent testing to validate its design and functionality, during which it demonstrated high sensitivity, reliably detecting saccadic eye movements with amplitudes as small as 1.0°. Ramp testing for evaluation of compatibility with flight systems confirmed that the GOE-Stim did not interfere with the aircraft's magnetometer or GPS systems, with magnetometer deviations remaining well below the failure threshold and GPS signal strength unaffected across all operational modes. EOG signal acquisition demonstrated minimal interference from aircraft systems, with physiological signals unaffected by engine start-up or cockpit interactions. In-flight testing further validated the device's safety and functionality, with uninterrupted operation and no interference with aircraft systems, including GPS.

The GOE-Stim headband advances wearable neurotechnology by providing a comfortable, functional solution for high-fidelity EOG signal acquisition in operational environments. It has been shown to be compatible with aircraft systems, offering stable performance. The integration of tVNS enhances its potential to mitigate fatigue and improve alertness. Although currently a research tool, the headband shows promise for field applications in human performance monitoring, decision-making, and neuroergonomics.