Development and Testing of a Transcutaneous Electrical Nerve Stimulation Device for Pilots

Neck/back pain is a significant problem for long-haul pilots. It accounts for an extensive burden in time and resources to the U.S. and international partners. Transcutaneous electrical nerve stimulation (TENS) is an established intervention for treating pain. However, existing solutions and form factors preclude use of such devices while flying.

We developed an innovative patented wrist-worn TENS device with large tactile buttons for operation through the flight suit. We assessed range of motion (ROM) in 26 participants using the device with either a neck or a back electrode. ROM was evaluated in standing position followed by seated position across 3 platforms (L-39, Mi-2, and B-737 simulator). Each subject also performed a 5-hour sortie in a B-737 simulator to evaluate long-duration performance, followed by a usability evaluation using the System Usability Scale (SUS). In a separate cohort of 9 participants, a 6-hour long-haul driving test was conducted to evaluate performance under high cognitive workload and non-stationary conditions. Device ergonomics were monitored throughout.

Evaluators achieved high percentages of unrestricted ROM assessments: 96.74% standing and 93.33% seated. Complete ROM restriction occurred for 1 participant in standing external rotation, 2 participants in seated throttle operation, and 1 participant during ingress. Cord length restriction during external rotation and ingress and device size during throttle operation were identified as root causes for the completely restricted ROMs. The mean SUS score across all subjects was 86.63. Long-haul driving testing revealed 1 inaccurate device activation across 100 trials. Line-of-sight (LOS) operation was initially noted but decreased in the latter half of the trials.

The current device design demonstrated high suitability and usability for both pilot and driver use in an operationally relevant environment. Root cause analysis of the observed restrictions identified design issues that can be easily addressed in future iterations. Future efforts should extend to testing the device's ergonomics during actual flying.