Acoustic & Ultrasonic

Mechanical pressure waves propagated into tissue, at frequencies where the interaction is wave propagation and focused energy deposition rather than structural loading — therapeutic ultrasound, LIFU, and (when the procedural rows arrive) HIFU. The dividing line from the mechanical family is physical, not stylistic: whether the body responds to the mechanical action as a loaded structure (Mechanical) or as a propagating medium (Acoustic). LIFU sits here for exactly that reason.

LIFU / tFUS — Low-Intensity Focused Ultrasound NeuromodulationLow-intensity focused ultrasound for neuromodulation. Re-filed to the Acoustic family (Δ16): the carrier is a propagating pressure wave with focused energy deposition, not a structural mechanical load and not, by carrier, a 'neuromodulation exception'. Low-intensity focused ultrasound can noninvasively reach deep and superficial brain targets with millimeter-scale spatial precision and reversibly modulate neural excitability, with reported effects that may be excitatory or inhibitory depending on the acoustic parameters used. Human evidence is early and parameter-sensitive: a systematic review of interventional human studies found both excitatory and inhibitory effects in motor and sensory regions while noting heterogeneity and incompletely understood mechanisms (Ho 2025), and early device and clinical work demonstrates feasible, well-tolerated targeting and preliminary cognitive signals (Bawiec 2025; JAMA Netw Open 2025). This is neuromodulation, not diagnostic ultrasound imaging — it should not be confused with full-body ultrasound scanning systems, which image anatomy and make no neuromodulatory claim.Insufficient evidence / under study grade C