Matching infrared wavelengths to skin improves local blood circulation in small human trial

Researchers from National Taiwan University, MacKay Medical University, and MacKay Memorial Hospital conducted a small study on a new approach to improve local blood circulation using infrared wavelengths. The study focused on a specific range of infrared wavelengths that align well with the skin's natural low-absorption properties near 10 μm.

This wavelength, around 10.3 μm, was chosen because silicon carbide (SiC), when used, emits thermal energy with epsilon-near-zero behavior, making it effective at targeting this wavelength and enhancing blood flow while avoiding unnecessary heating of the skin's surface.

In a controlled trial involving 25 healthy volunteers (50 hands), one hand was irradiated with a SiC emitter while the other received a conventional graphite emitter under identical heating conditions. After 20 minutes of treatment, the SiC emitter increased cutaneous blood flow by an average of 30.2%, compared to 18.6% with the graphite emitter. This significant difference suggests that spectral matching of the infrared wavelength with the skin's optical properties can lead to more efficient blood circulation enhancement.

Notably, blood pressure and heart rate remained unchanged, and skin temperature remained below 36°C (97°F), indicating the treatment's safety. The findings support the idea that wavelength-selective FIR emitters, like SiC, could be a more effective alternative to conventional broadband emitters for various biomedical applications, such as improving circulation, aiding wound healing, and other noninvasive therapies. Researchers suggest further studies to explore the clinical potential of this approach.