This feasibility study will evaluate a wearable focused ultrasound (FUS) system designed for non-invasive peripheral nerve stimulation of upper and lower extremity nerves. The primary objective is to determine device feasibility - operability, tolerability, usability, and physiological responses - during standardized pain sensitivity tasks.
Each participant will complete nine sessions on separate days (\~1 hour each) in a within-subject crossover design:
1. Cold pressor test (baseline, sham, active FUS) - 3 days
2. Upper limb algometry (baseline, sham, active FUS) - 3 days
3. Lower limb algometry (baseline, sham, active FUS) - 3 days
Sessions will be scheduled at least 24 hours apart to avoid carryover effects. Approximately 12-15 participants will be enrolled. Although feasibility studies often include fewer than 10 participants, this sample size was chosen to ensure variability across limb anatomy and usability testing. No efficacy hypotheses or clinical outcomes will be tested.
