An integrated CMOS optical sensing chip for multiple bio-signal detections

An integrated optical sensing chip for multiple bio-signal detections (MBSD) including peripheral capillary oxygen saturation (SpO ₂ ), pulse rate (PR), and fingerprint (TP) is proposed and prototyped in standard 0.18um CMOS technology. A MBSD CMOS optical sensing chip with a 128×64 dual-mode CMOS image sensor (CIS) array is implemented to achieve the multi-domain (temporal and spatial) signal detection using a single sensing array and shared LED source. In oximeter (OXI) mode (temporal-domain), the proposed sensing chip reports the continuous photoplethysmogram (PPG) signal for SpO ₂ calculation with a measured photo-sensitivity of 7.271nA/Lux, an achieved error of ±0.81% for R* ratio, a resulting error of ±1.01% for SpO ₂ , and a total power of 99μW (without LEDs). In optical fingerprint (OFP) mode (spatial-domain), the fingerprint pattern is successful demonstrated by captured images with a measured sensitivity of 1.983V/Lux*s and a low FPN of 0.098% at 30fps. *R = (AC of Red / DC of Red) / (AC of IR / DC of IR).