Based on devices that gain energy from the daily movement of a body, the hair growth technology described in the journal ACS Nano stimulates the skin with gentle, low-frequency electrical impulses that induce dormant follicles to reactivate hair production.
"I think this will be a very practical solution to hair regeneration," said Xudong Wang, a professor at the University of Wisconsin-Madison in the US.
The devices do not allow hair follicles to sprout in smooth skin. Instead, they reactivate sleeping, hair-producing structures, according to the researchers.
The technology can be used as an intervention for humans in the early stages of pattern baldness, but would not lead to cascading streaks on someone who has been "bald as a billiard ball" for several years.
Researchers discovered that because the devices are powered by the wearer's movement, they do not require a bulky battery or complicated electronics.
They are so inconspicuous that, according to the researchers, they could be discreetly worn under the crown of an everyday baseball cap.
Small devices, so-called nano-generators, passively collect energy from everyday movements and then transmit low-frequency electricity pulses to the skin.
This gentle electrical stimulation lets sleeping follicles "wake up," the researchers said.
"Electrical stimulation can support many different body functions," Wang said.
"Prior to our work, however, there was no really good solution for low-profile devices that provide gentle yet effective stimulation," he said.
Since the electrical impulses are incredibly gentle and do not penetrate deeper than the outermost layers of the scalp, the devices do not appear to cause any unpleasant side effects.
This is a distinct advantage over other baldness therapies such as the drug Propecia, which poses risks of sexual dysfunction, depression and feelings of anxiety, the researchers said.
In side-by-side tests on hairless mice, the devices stimulated hair growth as effectively as two different drugs used in hair loss medications.
"It is a self-activated system that is very simple and easy to use, and the energy is very low, so it causes minimal side effects," Wang said.