Flexible Dielectric Acoustic Resonator Patch for Tissue Regeneration

Ultrasound (US) therapy offers a non-invasive means of stimulating cellular activity, promoting tissue regeneration, and wound healing. However, current US transducers based on piezoelectric ceramics are rigid, mechanically incompatible with soft tissues, and thus unsuitable for wearable applications. To overcome these limitations, we developed dielectric patches that generate high-frequency acoustic waves using electrostatic resonance between interdigitated electrodes and a flexible polymer substrate. We identified the resonance frequency by analyzing the streaming motion of a droplet placed on the device surface while sweeping the frequency of the applied voltage. We fabricated a dielectric acoustic resonator patch (DARP) exhibiting acoustic resonance at 20 MHz by regulating IDE spacing and substrate thickness. The developed DARP maintained >95% of its acoustic output in the bending tests with 300 cycles regardless of the bending direction. The polyimide-based device exhibited ∼50% optical transmittance, which is beneficial for in situ imaging. Wound healing assays revealed that the migration speed of fibroblasts increased by 1.5-fold after 5 min of DARP stimulation. We also demonstrated that DARP was able to deliver acoustic energy into tissue-mimicking hydrogels with curved and planar surfaces. DARP can be applied to develop a platform for ultrasound-mediated wearable medical devices and regenerative therapies.