Fully Wearable Armband for Long-Term Peripheral Ultrasound Neuromodulation in Pain Management
William D. Moscoso-Barrera, Yiming Han, Jinmo Jeong, QiLiang Chen, Thomas Wynn, Mengxia Yu, Kai Wing Kevin Tang, Mengmeng Yao, Ju-Chun Hsieh, David Wu, Landon Gauthreaux, Xiang Qian, Yaoyao Jia, Huiliang Wang
2025 · 10.1101/2025.10.29.25339092
Abstract
Chronic pain is a leading cause of medical consultations, often managed with opioids despite their high risk of addiction. Low-Intensity Focused Ultrasound (LIFU) neuromodulation has emerged as a promising non- invasive alternative for pain management. However, effective pain modulation often requires prolonged or continuous stimulation, and current LIFU devices are typically bulky and tethered to external power sources, limiting their applicability as wearable technologies for long-term use. This study introduces a fully wearable LIFU-based armband designed for peripheral nerve stimulation in pain management. It integrates a concave piezoelectric transducer, an acoustic hydrogel sheet for strong adhesion and extended use, as well as a miniaturized electronic circuit with a lithium-ion battery in a fabric armband for comfortable placement. LIFU was applied to the median nerve, and its effects on pain thresholds were evaluated in healthy volunteers using pressure algometry and cold pressor tasks. Results showed a significant increase in pain thresholds, with an average rise of 15%. These findings support the potential of wearable LIFU neuromodulation as a noninvasive and portable therapy for chronic pain management.
Abstract via europepmc.
Exposures
Exposure 1: Median nerve at the antecubital fossa, wearable concave transducer
Target: median nerve — “median nerve in the antecubital fossa”
Device: custom-built · Del Piezo (piezoelectric element supplier) · PerNeUS concave PZT transducer (DL-47); driven by IGT BBBoq or custom battery circuit ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 650 | ✓✓✓ |
| Pulse duration (ms) | 5 | ✓✓✓⚑ |
| Pulse repetition frequency (Hz) | 100 | ✓✓✓⚑ |
| Duty cycle (%) | 50pulse duration × PRF gives 50% | ✓✓✓ |
| Sonication duration (s) | 300 | ✓✓✓⚑ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | 41.4 | ✓✓✓ |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported |
650 kHz bursts of 200 ms (BD) gated 5 ms on / 5 ms off (50% duty cycle, repeated 20 times), burst repetition frequency 100 Hz, delivered every 2 s (inter-stimulus interval) for a total sonication duration of 5 min; the fully wearable device was described as 136 repetitions every 2 s.
Flags from extraction
exposures[0].timing.pulse_duration_ms— Burst rule: the paper calls 200 ms the burst or pulse duration (and says a 5 ms pulse is emitted), while 50% duty cycle at 100 Hz implies 5 ms pulses; 5 ms recorded as the pulse and 200 ms as the train.exposures[0].timing.sonication_duration_s— Recorded 0.2 s for one 200 ms burst; the paper's 'sonification duration' of 5 min is the whole session (repeated every 2 s). The 136 repetitions at 2 s would give about 4.5 min, not 5 min.exposures[0].timing.pulse_repetition_frequency_hz— Paper names 100 Hz both a pulse repetition frequency and a burst repetition frequency.exposures[0].unspecified_domain.isppa_w_cm2— Isppa 41.4 W/cm2 is given in the Discussion as measured; acoustic characterisation was done in a deionised water tank but the sentence does not name the domain. A pressure of about 0.57 MPa at 30 V is also given but is not tied to the stimulation setting.n_subjects— Separate experiments used 8 (commercial driver, PA), 8 (CPT), 4 + 4 (wearable circuit), 4 + 4 (duration) and 3 (hydrogel durability) volunteers; overlap between experiments is not stated. Recorded as the list of experiment sizes taken from the text ([8,4,4,4,4,3]), quote shows n=8 only.exposures[0].device.family— Transducer built in-house from a Del Piezo PZT element; driven by an IGT BBBoq system in the commercial-driver experiments and a custom circuit otherwise.sham_type— Sham stimulation is mentioned as randomised and counterbalanced but not described.direction_of_effect— Outcome is increased pain threshold (authors infer inhibition of nociceptive signalling).exposures[0].target.terms— Protocol states median nerve localised at the antecubital fossa; pain thresholds were measured at the hand.