An Integrated CMOS Photodiode Array for Highly Sensitive Photometric Diagnostics

This work describes the development and test of an integrated CMOS photodiode sensor array for bioanalytical applications. The integrated circuit (IC) was optimized for light absorption measurement and low-cost system integration. The CMOS-based measurement system was tested and compared to a commercial optical power meter. Opto-electrical measurement results prove a measurement range of three decades with a detection limit of the optical density OD = 0.001 in air at maximum sensitivity. Furthermore, we demonstrate the system usability for bioanalytical characterization performing a quantitative detection of gold nanoparticles (NP) deposited on the CMOS photodiodes. Therefore, measurements show a minimum detectable mean value of OD = 0.009, which corresponds to a small particle number of 38900 on top of the photodiode sensor surface. This CMOS based photometric measurement approach states the possibility to be used in low-cost, quantitative photometric diagnostic systems for medical applications e.g. for early cancer recognition.