Biofunctionalized all-polymer photonic lab on a chip with integrated solid-state light emitter

A photonic lab on a chip (PhLOC), comprising a solid-state light emitter (SSLE) aligned with a biofunctionalized optofluidic multiple internal reflection (MIR) system, is presented. The SSLE is obtained by filling a microfluidic structure with a phenyltrimethoxysilane (PhTMOS) aqueous sol solution containing a fluorophore organic dye. After curing, the resulting xerogel solid structure retains the emitting properties of the fluorophore, which is evenly distributed in the xerogel matrix. Photostability studies demonstrate that after a total dose (at λ=365 nm) greater than 24 J cm^-2, the xerogel emission decay is only 4.1%. To re-direct the emitted light, the SSLE includes two sets of air mirrors that surround the xerogel. Emission mapping of the SSLE demonstrates that alignment variations of 150μm (between the SSLE and the external pumping light source) provide fluctuations in emitted light smaller than 5%. After this verification, the SSLE is monolithically implemented with a MIR, forming the PhLOC. Its performance is assessed by measuring quinolone yellow, obtaining a limit of detection (LOD) of (0.60±0.01) μM. Finally, the MIR is selectively biofunctionalized with horseradish peroxidase (HRP) for the detection of hydrogen peroxide (H₂O₂) target analyte, obtaining a LOD of (0.7±0.1) μM for H₂O₂, confirming, for the first time, that solid-state xerogel-based emitters can be massively implemented in biofunctionalized PhLOCs.