Abstract: A wearable device for transdermal product supply comprises a head, which houses two ultrasonic resonators in resonance, with an outer cavity. A first, more distal resonator emits towards the skin at a first frequency and a second, more proximal resonator surrounds the cavity and emits parallel to the skin at a second frequency. One frequency is high-frequency sonophoresis (HFS) and the other is low-frequency sonophoresis (LFS). The second resonator comprises a hole in order to enable the waves from the first resonator to pass through. The waves from the second resonator pass through the head, the hole and the cavity, bouncing off an opposite area of the head and interfering with the waves from the first resonator. The interference between the waves creates a stationary field which increases the permeability of the skin, enabling a device with a reduced size to be incorporated into a wearable.