A wearable device for regrowing hair (Nanowerk News) Although some people embrace the saying "bald is beautiful," for others, alopecia, or excessive hair loss, can cause stress and anxiety. Some studies have shown that stimulating the skin with lasers can help regrow hair, but the equipment is often large, consumes lots of energy and is difficult to use in daily life.

Now, researchers have developed a flexible, wearable photostimulator that speeds up hair growth in mice. They report their results in ACS Nano ("Trichogenic Photostimulation Using Monolithic Flexible Vertical AlGaInP Light-Emitting Diodes").

Treating shaved mice with flexible vertical µLEDs (f-VLEDs) regrows hair faster than no treatment (Con) or minoxidil injections (MNX). (Image: ACS)

Affecting millions of men and women worldwide, alopecia has several known causes, including heredity, stress, aging and elevated male hormones. Common treatments include medications, such as minoxidil, corticosteroid injections and hair transplant surgery. In addition, irradiating the bald area with a red laser can stimulate hair follicles, causing cells to proliferate.

However, this treatment is often impractical for home use. So, Keon Jae Lee and colleagues wanted to develop a flexible, durable photostimulator that could be worn on human skin.

The team fabricated an ultrathin array of flexible vertical micro-light-emitting diodes (µLEDs). The array consisted of 900 red µLEDs on a chip slightly smaller than a postage stamp and only 20 µm thick.

The device used almost 1,000 times less power per unit area than a conventional phototherapeutic laser, and it did not heat up enough to cause thermal damage to human skin.

The array was sturdy and flexible, enduring up to 10,000 cycles of bending and unbending. The researchers tested the device's ability to regrow hair on mice with shaved backs.