Enhanced Stimulated Raman Scattering Biosensing Platform for Low-Power Metabolic Monitoring via Open-Geometry Design and Optimized Electronic Modulation

Abstract Stimulated Raman scattering (SRS) microscopy is a powerful tool for biomedical biosensing, yet its widespread application is often hindered by high phototoxicity and restrictive “sandwich-type” sample preparation. Conventional setups limit real-time experimental manipulations and require high-power excitation to achieve sufficient signal-to-noise ratios, limiting their utility for sensitive live-cell kinetic studies. This work presents an enhanced SRS biosensing platform designed for noninvasive, low-power monitoring of dynamic metabolic processes. The system’s performance is driven by three synergistic innovations: 1/an optical design allowing in situ reagent addition in standard glass-bottom dishes, 2/a low-repetition-rate (20 MHz) picosecond laser source to increase pulse energy and enable operation in a low-average-power regime suitable for live-cell imaging, and 3/a patented direct modulation scheme that synchronizes an acousto-optic modulator with an internal lock-in oscillator. The platform’s capabilities were validated by tracking the kinetics of early uptake of deuterated palmitic acid in live HL-60 cells. Results demonstrate high-fidelity detection of metabolic tracers within minutes of supplementation, resolving spatiotemporal accumulation into lipid droplets under low-illumination conditions. The combination of optimized electronic demodulation and flexible optical design provides a robust and enhanced biosensing solution for long-term in situ investigation of dynamic biochemical transformations in living cells.