This study will evaluate the feasibility of a novel wearable focused ultrasound (FUS) device for peripheral nerve stimulation in healthy volunteers. The aim is to assess device operability, usability, tolerability, and physiological responses during standardized sensory tests. Each participant will complete nine \~1-hour study sessions across multiple days, including cold pressor and algometry tasks performed under baseline, sham, and active FUS conditions.
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.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
DEVICE_FEASIBILITY
Masking
SINGLE
Enrollment
8
This study uses a three-session cold pressor paradigm to evaluate feasibility of a wearable focused ultrasound (FUS) device for peripheral nerve stimulation. Session 1 (Baseline): After consent, participants immerse the dominant hand in 0-1 °C water (\~10 cm depth) in an insulated bucket. Time to first pain is recorded, with 5 min rests between immersions (12 total; max single immersion 6 min). Water temperature is digitally monitored, with ice added as needed. Session 2 (Sham): The median/ulnar/radial nerve in the dominant forearm is located by ultrasound. The FUS device is applied with hydrogel but set to sham (no output). The cold pressor protocol is repeated. Session 3 (Active FUS): After nerve localization, active FUS (650 kHz, 60-100% intensity, 20-30% duty cycle) is delivered for 5 min. The cold pressor test is repeated to record pain tolerance as an exploratory physiological response during feasibility testing.
This session records pressure pain thresholds in the dominant hand with a wearable FUS device and a pressure algometer during feasibility testing. Session 1 (Baseline): After consent and briefing, the median, ulnar, and radial nerves at three points on the dominant hand (wrist, palm, finger) are located via ultrasound and marked. A pressure algometer is applied to each site, with pressure gradually increased until pain is first reported. Thresholds are recorded, with each location tested three times with short breaks. Session 2 (Sham): The same nerve sites are identified and marked. The wearable FUS device is applied with hydrogel but set to sham (no active output). The baseline algometry protocol is repeated. Session 3 (Active FUS): Following nerve localization, active FUS (650 kHz, 60-100% intensity, 20-30% duty cycle) is delivered for 5 min. The algometry test is repeated to record pressure pain thresholds as exploratory physiological responses during feasibility testing.
Biomedical Enginering Building - UT Austin
Austin, Texas, United States
Completion Rate of Study Sessions
Proportion of participants who complete all nine planned sessions (baseline, sham, active FUS for cold pressor, upper limb algometry, and lower limb algometry) without withdrawal or device malfunction.
Time frame: Through study completion (9 study visits over approximately 3 weeks).
Cold Pressor Pain Onset Time
Time (seconds) from immersion of the hand in ice water until pain is first reported; measured during baseline, sham, and active FUS sessions to characterize physiological response during feasibility testing (not powered for efficacy).
Time frame: 3 separate study visits (~1 hour each) over approximately 1 week.
Upper Limb Algometry Pain Threshold
Maximum tolerated pressure (kgf) at standardized points on the hand and forearm before pain is reported, measured using a pressure algometer during baseline, sham, and active FUS sessions. Recorded as an exploratory physiological response during feasibility testing.
Time frame: 3 separate study visits (~1 hour each) over approximately 1 week.
Lower Limb Algometry Pain Threshold
Maximum tolerated pressure (kgf) at standardized points on the foot before pain is reported, measured using a pressure algometer during baseline, sham, and active FUS sessions. Recorded as an exploratory physiological response during feasibility testing.
Time frame: 3 separate study visits (~1 hour each) over approximately 1 week.
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This session records pressure pain thresholds in the dominant foot with a wearable FUS device and a pressure algometer during feasibility testing. Session 1 (Baseline): After consent and briefing, the tibial, saphenous, and peroneal nerves at three standardized points on the dominant foot are located via ultrasound and marked. A pressure algometer is applied to each site, and pressure is gradually increased until pain is first reported. Thresholds are recorded, with repeated trials and short breaks between tests. Session 2 (Sham): The same nerve sites are identified and marked. The wearable FUS device is applied with hydrogel but set to sham (no active output). The baseline algometry protocol is repeated. Session 3 (Active FUS): Following nerve localization, active FUS (650 kHz, 60-100% intensity, 20-30% duty cycle) is delivered for 5 min. The algometry test is then repeated to record pressure pain thresholds as exploratory physiological responses during feasibility testing.