Skin-to-Muscle Deep Tissue Stimulation System for Muscle Atrophy.

Abstract

With the rapidly growing global aging population, muscle atrophy affects ≈40% of older individuals, leading to severe impairments in daily activities. However, its treatment remains challenging due to adverse effects associated with drug accumulation, the difficulty of delivering drugs specifically to deep muscle tissues, and the inherent limitations of current therapeutic devices that rely on wired connections or battery-dependent external power systems. In this study, a body-coupled on-target stimulation (BOOST) system is introduced in combination with an active releasing muscle stimulation (ARMS) hydrogel, which possesses anti-drying properties and enables electroactive drug release. The BOOST system enables battery-free, wirelessly delivered electrostimulation and simultaneous drug delivery from the skin to deep muscle layers by leveraging charge accumulation in tissue capacitance. This in-body field amplification generates a muscle-targeted electric field that enables deep-tissue drug penetration. In addition, when combined with the electro-responsive ARMS hydrogel containing electrically bound dexamethasone phosphate (Dex) molecules, the BOOST system exhibits synergistic performance, achieving targeted internal electrostimulation and efficient Dex penetration into deep muscle tissue for effective transdermal-to-muscle delivery. The simultaneous application of ES and Dex effectively restores muscle cells severely damaged by oxidative stress, mimicking the pathological conditions of muscle atrophy.