Conformable Ultrasound Face Patch for Cavitation-enhanced Transdermal Cosmeceutical Delivery

Abstract

Increased consumer interest in healthy-looking skin demands a safe and effective method to increase transdermal absorption of innovative therapeutic cosmeceuticals. However, permeation of small-molecule drugs is limited by the innate barrier function of the stratum corneum. In this thesis, we develop a conformable ultrasound face patch (cUFP) that closely adheres to the facial skin to aid in the penetration and absorption of cosmeceuticals across the epidermis and dermis layers of the skin. A novel face mask design with piezoelectric transducers embedded in a soft elastomer substrate is fabricated and investigated, starting from a single-element prototype and subsequently a full two-dimensional array. Localized pockets of fluid coupling medium are created between the cUFP and skin. This approach provides sufficient reservoir space for inertial cavitation, convective mixing, and microjet formation with the application of ultrasound. Multiphysics simulation models are used to guide parameters for device design, and the modeling outputs are verified with electrical and mechanical characterization results. Subsequently, acoustic spectrum analysis and high-speed videography are conducted to elucidate a holistic understanding of the cavitation mechanism generated by intermediate-frequency sonophoresis. Together, the simulation model, electromechanical and acoustic characterization, and cavitation visualization help guide the operating parameters for the in vitro permeation study, which is conducted to test the efficacy of the cUFP in enhancing transdermal permeation. The final system demonstrates a 26.2-fold enhancement in niacinamide transport in a porcine skin model in vitro with a 10-minute ultrasound treatment, demonstrating the suitability of the device for short-exposure, large-area application of sonophoresis for patients and consumers suffering from skin conditions, damaged skin barriers, and premature skin aging.