BPS2026 - Dual-mode plasmonic imaging system for spatiotemporal monitoring of biological events

Understanding core biological processes is crucial for elucidating fundamental life mechanisms. These processes span nanometers to micrometers and occur within milliseconds to seconds, exhibiting strong spatiotemporal dynamics. Surface plasmon resonance imaging (SPRi) offers a promising solution to capture biological events with both high spatial precision and rapid dynamics. Commercial SPRi systems support high-throughput assays but typically rely on microarray spots hundreds of micrometers wide, limiting lateral resolution and diluting signals by background. To overcome these limitations, we developed a plasmonic chip integrating surface plasmon resonance (SPR) and plasmon waveguide resonance (PWR), generating dual sensing regions for the interior and exterior of micrometer-scale pore arrays. Incorporated into a custom dual-mode imaging system, the chip provides a tunable field of view from 0.4 to 2.4 mm 2 , ∼60 ms temporal resolution, and ∼3 μm lateral resolution. Imaging distinct resonance modes enabled discrimination of signals inside and outside pores, additionally providing depth-resolving capabilities beyond conventional SPRi. Each pore functions as an individual sensing spot, yielding thousands of localized sites per field of view to enhance throughput while reducing signal dilution. Coupling with a microfluidic channel to create concentration gradients enables multiplexed measurements under distinct conditions. We validated the system by monitoring glucose transport across nanometer-thick membranes reconstituted on the chip. Transporter-containing membranes spanned the pores, separating intra- and extra-pore compartments. A glucose gradient introduced via the microfluidic channel served as stimulation. PWR-associated imaging reported bulk glucose concentration, while SPR-associated imaging revealed transport into pore interiors. Distinct responses under varying glucose levels confirmed the resolving power and multiplexing capacity of the platform. Collectively, these results establish a label-free, high-resolution optical imaging platform capable of real-time, multiplexed monitoring. This approach opens new opportunities to study fundamental biological processes with high spatial and temporal fidelity.