Hair loss treatments could soon become much easier and more effective, as researchers from the the Korea Advanced Institute of Science and Technology (KAIST) have a new phototherapy device that can be worn as a hat.
Instead of relying on heavy, rigid equipment—like classic helmet-style phototherapy devices—this new technology uses a soft, cap-like OLED-based wearable.
In tests, the hat has been shown to suppress the aging of hair follicles—a key factor in hair-loss progression—by up to 92 percent.
While drug-based treatments for hair-loss are known to be effective, experts are concerned over possible side-effects from prolonged use, driving more interest in safer alternatives such as phototherapy.
However, despite this growing interest, existing phototherapy devices have clear limitations. Most are bulky, helmet-style devices that are uncomfortable to wear and often confined to indoor use. Moreover, their use of point light sources like LEDs or lasers makes it difficult to deliver uniform irradiation across the entire scalp.
The research team addressed these issues by replacing point light sources with area-emitting OLEDs, which produce uniform light across a wide surface. Near infrared OLEDs were incorporated into a soft, fabric-like material that can be worn as a cap.
Because of the flexibility of the material, the new device naturally follows the contours of the scalp, allowing consistent light exposure over the entire scalp.
But comfort was not the only goal of the study. “A key outcome of this study is demonstrating that precisely engineered light wavelengths can effectively suppress hair-follicle cell aging,” paper author and electrical engineer Eun Hae Cho said in a statement.
The team also focused on optimizing the light wavelength employed, as different wavelengths can trigger different cellular responses. They adapted wavelength-control techniques originally developed for display OLEDs for therapeutic use.
Using this approach they designed custom OLEDs that emit near infrared light in the 730 to 740 nanometer range, which is optimal for activating dermal papilla cells—critical cells located at the base of hair follicles that regulate hair growth.
To test the device’s effectiveness, the researchers conducted experiments using human dermal papilla cells (hDPCs), and found that exposure to near infrared OLEDs light reduces cellular aging by approximately 92 percent, outperforming conventional red-light irradiation conditions.
“Going forward, we plan to verify safety and efficacy through preclinical studies and progressively evaluate the potential for real therapeutic applications,” concluded paper author professor Kyung Cheol Choi.
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Reference
Cho, E. H., An, J., Chi, Y., & Choi, K. C. (2026). Wearable textile-based phototherapy platform with customized NIR OLEDs toward non-invasive hair loss treatment. Nature Communications. https://doi.org/10.1038/s41467-025-68258-3