Large-Area Biocompatible Random Laser for Wearable Applications

Area of Science:

• Biomedical Engineering
• Materials Science
• Optics

Background:

• Wearable sensor technology is crucial for health monitoring.
• Existing sensors have limitations in customization and large-area application.
• Random lasers offer unique properties for sensing applications.

Purpose of the Study:

• To design a simple, cost-effective fabrication method for large-area biocompatible random lasers.
• To customize wearable sensors using random laser technology.
• To explore the potential of these lasers for motion and humidity sensing.

Main Methods:

• Fabrication of a large-area random microcavity using polymethyl methacrylate (PMMA) as a matrix.
• Incorporation of rhodamine B (RhB) as a gain medium and gold nanorods (Au NRs) for plasmonic feedback via spin-coating.
• Optical excitation to achieve coherent random lasing.

Main Results:

• Successful attainment of coherent random lasing with a narrow linewidth (~0.4 nm) at a low threshold (~23 μJ/cm²).
• Demonstration of tunable lasing wavelength (612.6–624 nm) by mechanically altering Au NR spacing in the flexible film.
• The tuning process was found to be recoverable.

Conclusions:

• A designable and simple method for fabricating large-area biocompatible random lasers was demonstrated.
• The flexible random laser film shows potential for wearable applications, including motion and relative-humidity sensing on human skin.
• This technology advances the development of customized wearable sensors.