Plasmon‐Mediated Transdermal Ultrasonic Photo‐Elastic Patch for Efficient Drug Delivery

Transdermal permeation is often restricted by the stratum corneum, necessitating either chemical enhancers or wired sonophoresis hardware. A compact, flexible, laser‐activated cavitation patch that converts nanosecond optical pulses into mid‐frequency (≈100 kHz) ultrasound, generating inertial cavitation in a 1 mm‐deep micro‐reservoir directly above the skin, is demonstrated. A 50 nm gold (Au) film on a quartz disc serves as an opto‐acoustic transducer and is encapsulated in an elastomer scaffold that conforms to curved surfaces, sealing the drug reservoir. Multiphysics modeling predicts peak pressures of ≈3 MPa at the laser focus and greater than 0.2 MPa at a 3 millimeter tissue depth; hydrophone and high‐speed videography corroborate these values. Ex vivo porcine‐skin assays show that a 3‐minute exposure at 290 mW increases the cumulative flux of niacinamide eight‐ to tenfold and extends its penetration depth to ≈450 microns. At the same time, vitamin C reaches ≈650 microns with a temperature increase limited to below 3 °C. The battery‐free architecture, sub‐cm 2 drug induction sites, and raster‐scan free wide area scalable delivery system fabrication position the device as a promising platform for on‐demand dermatological therapy and precision cosmeceutical delivery.