A More-Than-Moore Optical Multisensing Platform

This work demonstrates the integration of a photoluminescent sensing film on a CMOS sensor ASIC for time-resolved optical oxygen sensing. A phosphorescent dye, Platinum Octaethyl Porphyrin (PtOEP), embedded in a Polydimethylsiloxane (PDMS) matrix, was deposited on the ASIC using spin-coating and photolithographic patterning. The custom ASIC includes an array of closely spaced SiLED emitter and SPAD detectors with the capability of multimodal sensing. The platform benefits from the dye’s long emission lifetime, resistance to photobleaching, and the intrinsic nature of the lifetime measurement concerning the analyte and dye. A custom Printed Circuit Board (PCB) incorporating a Time-Correlated Single Photon Counting (TCSPC) module based on an ARM Cortex-M7 microcontroller was developed to drive the sensor and acquire nanosecond-resolution photon timing data. The integrated sensor system was rigorously characterised in a controlled gas chamber, showing reliable oxygen detection via luminescence quenching and strong Stern-Volmer linearity (R² = 0.9771). It exhibited excellent repeatability (<5% variation across cycles) and fast, real-time response. In order to demonstrate multimodal sensing, we integrated multiple oxygen-sensitive dyes—PtOEP, Palladium Octaethyl Porphine (PdOEP), and Zinc Octaethyl Porphyrin (ZnOEP)—over different CMOS regions. The system was adapted for multi-analyte sensing without cross-sensitivity, highlighting its potential for biomedical applications in hypoxic environments.