For a beauty device to have anti-aging effects, the radio frequency (RF) needs to reach the dermis and generate heat that can warm collagen. Therefore, it must meet at least two standards: temperature and RF depth.
The penetration depth and temperature of RF are related to electrode distance, RF frequency, power, etc. It requires systematic design and multiple tests. The final result is a balance between multiple parameters. Therefore, a single parameter can be used as a reference, but it is not absolute.
1. The number of electrodes is related to the RF effect. RF devices can be classified according to the RF electrodes, mainly including monopolar RF, bipolar RF, and multipolar RF.
Monopolar RF has strong penetration, deep penetration, and good effects, but it is very painful and is mostly used in medical devices.
Bipolar RF has one positive and one negative electrode, with current flowing between the two electrodes. The penetration depth is approximately half the distance between the two electrodes. The disadvantage is that the energy method is fixed, requiring increased power to increase energy, and it also lacks depth variation.
Multipolar radiofrequency (RF) consists of three or more electrodes. All electrodes alternately exchange positive and negative charges, forming a current loop between any two electrodes. Multiple current loops concentrate the treatment energy, allowing for sufficient energy to be obtained with relatively low power, thus rapidly increasing the temperature of the skin tissue in the treatment area.
2. Higher power is not always better. Power refers to the energy that powers the electromagnetic waves emitted by the beauty device. With a fixed number of electrodes, generally, higher power results in higher temperatures. Many medical aesthetic devices have power ratings as high as 300W.
However, for safety reasons, the power of home-use beauty devices should not be increased indiscriminately. Continuous contact with a 43°C heat source for 6 hours can cause irreversible damage to the basal cells of the skin. A 70°C heat source, even continuous contact with the skin for just 1 minute, can cause damage to the entire epidermis.
3. Higher frequency, faster heating. The frequency of RF affects the heating speed and depth of action of the beauty device.
Higher frequency means faster RF oscillation and faster heating. Lower frequency means a greater distance and deeper RF oscillation.
Home-use beauty devices typically combine this with the number of electrodes, and there are two common approaches:
A. 1-2MHz variable frequency + 4 electrodes, exemplified by Ya-Man
B. 1MHz constant frequency + 6 electrodes, exemplified by Amiro
Both are safe and effective methods, and there's little difference in usage; the only difference is the way they work.
4. The closer the probe is to the skin, the less energy is lost.
The effectiveness of radiofrequency is also related to the actual energy reaching the skin. The human body itself is a resistor; for radiofrequency energy to reach the dermis, resistance needs to be reduced. Applying gel and using metal probes serve this purpose.
If the probe doesn't fit snugly against the skin, poor contact can easily lead to energy loss, resulting in less energy reaching the dermis. Home-use beauty devices already have very low energy output, and such waste is unacceptable.