Tunable Acoustic Layers Enable Gel‐Free, Conformal Wearable Ultrasound

Rigid probes and coupling gels still tether diagnostic ultrasound to the clinic, precluding continuous use on moving, curved, sweating human skin. We report a tunable design platform based on epoxy–polyetheramine composites enabling independently tuned matching and backing layers, spanning ranges of acoustic impedance (2.0–5.4 MRayl), attenuation (12–117 dB·cm −1 at 2.25 MHz), and Young's modulus (4–4700 MPa). A gradient‐impedance matching layer lifts fractional bandwidth from 15% to 54%, while the visco‐elastic backing boosts signal‐to‐noise‐ratio (SNR) by 9 dB without sacrificing conformity. In vivo validation through blood pressure measurements demonstrates the efficacy of these tailor‐designed transducers in capturing key hemodynamic parameters, enabling continuous cardiovascular monitoring beyond traditional clinical settings. This versatile platform translates polymer network chemistry into a design process, offering a general path to gel‐free wearable ultrasound and, more broadly, to on‐skin acoustic, photo‐acoustic, and therapeutic devices.