Controlled Thermal Stimulation Using 980‐nm Laser for Collagen Remodeling

Collagen plays a key role in maintaining skin structure and function. Energy based devices such as radiofrequency and ultrasound stimulate collagen synthesis through thermal stimulation, but lack precise temperature regulation. This study evaluated collagen synthesis induced by controlled thermal stimulation using a 980 nm laser. An ex vivo test identified conditions to achieve 50°C-60°C. Based on these results, 2.5 W laser irradiation for 35 s was applied to in vivo rat skin. Skin samples were collected on days 0, 14, and 28. Histology showed a three-fold increase in dermal thickness and a 15% increase in collagen density at day 28. RT-qPCR confirmed upregulation of FGF2, AKT, and COL3A1, with no significant changes in IL-1β or IL-6, and decreased NF-κB expression, indicating minimal inflammation. These findings demonstrate that controlled 980 nm laser stimulation enhances collagen synthesis without damaging skin tissue. Future studies will assess thermal distribution using fiber Bragg grating sensors.