Fractional Microneedle Radiofrequency and Conductivity

Fractional microneedle radiofrequency (which we will describe in this book as needle RF for) is a device that inserts needles into a skin (minimally invasive) and allows a bipolar radiofrequency (RF) current to flow through to achieve collagen remodeling. RF has a frequency set for each device, and the needle RF I use uses 2 MHz (Table 13.1). Intensity can be adjusted from level 0 to 100 (%). A repetition refers to the time between pulse durations, which corresponds to frequency (Hz) in lasers. For example, repetition 0.2 s corresponds to 5 Hz. Repetition refers to the time it takes to move the handpiece from one point to another rather than affecting the treatment results, and I usually use 0.5–0.8 s. The needle is a non-insulated needle that is 0.3 mm thick and there are 2 pins; 25 pins with 25 needles arranged 5 × 5 and 16 pins with 16 needles arranged 4 × 4. I mainly use the 25 pin. The biggest advantage of needle RF is that the needle depth can be adjusted, from 0.5 to 3.5 mm. The pulse duration can be adjusted from 50 to 590 ms, but there is no repeat mode by which the current flows or stops repeatedly like the macropulse of the pulsed dye laser (PDL). Recently, there is also a needle RF that can calibrate impedance or temperature correction. The equipment I use cannot calibrate impedance or temperature.