Silica based biocompatible random lasers implantable in the skin

We demonstrate efficient random lasing from microslices containing dye-doped colloidal silica nanoparticles. The nanoparticles with diameters of 20 nm were synthesized by a modified Stober method, having a high emission efficiency and well dispersed in an aqueous medium. From the suspension of the nanoparticles, a film is created via self-assembly of colloidal nanoparticles. After grinding the film, microslices with dimensions of around 100-200 mu m and thickness of 2 mu m are obtained. Under optical pulse excitation, these microslices emit random lasing. The lasers operate well in the air and also in water. Their emission spectrum and lasing threshold in both conditions are studied and compared. Interestingly, lasing emission can be observed from a laser embedded into the porcine skin tissue. Our work provides a simple technique and architecture for biocompatible random lasers which have potential for biosensing and biological probes.