Biocompatible microlasers based on polyvinyl alcohol microspheres

Biocompatible microlasers, generally made of bio-derived materials, are promising for biosensing and cell-tracking. These kinds of lasers offer favourable opportunities like biocompatibility and biodegradability but the materials used often require complicated synthesis and high cost. In this work, we demonstrate that polyvinyl alcohol (PVA), a synthetic water-soluble low-cost polymer, with fascinating properties such as good transparency, biocompatibility, biodegradability is an excellent candidate for making laser cavity. Using a simple and effective technique, dye-doped PVA microspheres can be fabricated with various sizes from 10 to 200 μm. These microspheres can act as excellent lasers under optical excitation with a lasing threshold of ∼2 μJ/mm2 and Q factor of lasing modes of ∼3000. The lasing mechanism is studied and it is ascribed to whispering gallery mode (WGM). Size-dependent lasing characteristics including lasing spectrum, quality (Q) factor and lasing threshold are investigated. Owing to the ease of fabrication, the cost-effectiveness, the biocompatibility of the PVA material, our biocompatible microlasers are promising for future biosensing applications. © 2019 Elsevier B.V.