Optics-Free Bioluminescence Detection on a CMOS Camera Chip

Sammanfattning

This thesis explores the development of a compact, optics free and low-cost biosensing platform based on direct on-chip detection of bioluminescence using a complementary metal–oxide–semiconductor (CMOS) image sensor. This work is motivated by the need and challenge of combining the high sensitivity of optical biosensing in laboratories with the simplicity and portability required for point-of-care applications. More specifically, we calibrated a commercial CMOS camera sensor and evaluated it as a quantitative detector for low-light measurements by characterizing its responsivity, linearity, noise floor, and saturation behavior under controlled LED illumination. In parallel, we expressed, purified and characterized a bioluminescent reporter system based on NanoLuc luciferase using UV–Vis spectroscopy and SDS–PAGE analysis. Lastly, we integrated these two elements into a biosensing device using accessible methods, including 3D-printed components and a PDMS sample well positioned directly above the sensor surface area. Baseline experiments demonstrated successful direct detection of NanoLuc bioluminescence down to 10nM, using the CMOS platform, while a microscopy-based setup served as a reference system for comparison. To improve detection sensitivity under weak-signal conditions below 10 nM, we proposed and demonstrated a signal enhancement approach based on lock-in amplification using a microfluidic modulation platform in a microscope-based setup. These findings highlight the potential of modulation-based signal processingfor future highly sensitive and portable optical biosensing applications.