Spatially Encoded Photonic Microsphere Lens Arrays with Deterministic Hotspaces Enabling Optofluidic Surface-Enhanced Raman Scattering Chip for Dynamic Monitoring of Multiple Biomarkers

Abstract

Real-time, quantitative dynamic monitoring of multiple biomarkers is urgently needed in clinical practice; however, conventional technologies are limited by cumbersome workflows and time-consuming operational procedures. Surface-enhanced Raman scattering (SERS) offers high sensitivity and molecular fingerprinting capability, but its application in dynamic monitoring is restricted by signal instability caused by signal irreproducibility arising from stochastic hotspot analyte spatial mismatches, and an exclusive reliance on endpoint measurements that precludes kinetic information extraction. Hence, we present an optofluidic SERS chip integrating spatially encoded photonic microsphere lens arrays (SE-PMLAs) with deterministic hotspaces to overcome these limitations. Through precise integration of gold nanoparticles onto microsphere lens surfaces, each functional unit achieves cascaded photonic–plasmonic coupling among photonic nanojets, whispering-gallery modes, and localized surface plasmon resonance, with near-field feedback reinforcement that transforms random hotspots into engineered, uniform hotspaces, delivering an average enhancement factor of 2.8 × 1010 and signal uniformity with a relative standard deviation below 5%. Using spatially encoded sensing, we demonstrate single-sample, synchronous high-throughput detection of influenza A/B viruses, adenovirus, and monkeypox virus, achieving limits of detection of 0.53 pg/mL, 128.85 copies/mL, 199.56 copies/mL, and 2.7 pg/mL, respectively. Crucially, the chip's ultrastable signal output enables a kinetic quantification model based on the initial binding rate, revealed a linear correlation between analyte concentration and its initial binding rate (i.e., slope). This approach achieves rapid, high-precision dynamic monitoring within 60 to 120s while expanding the linear detection range by two orders of magnitude. Ultimately, this chip delivers a robust, minute-level point-of-care solution for real-time pathogen screening and critical disease diagnostics.