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A Single-Chip CMOS Pulse Oximeter with On-Chip Lock-In Detection.

He D, Morgan SP, Trachanis D, van Hese J, Drogoudis D, Fummi F, Stefanni F, Guarnieri V, Hayes-Gill BR - Sensors (Basel) (2015)

Bottom Line: The experimentally measured AC and DC characteristics of individual circuits including the DC output voltage of the transimpedance amplifier, transimpedance gain of the transimpedance amplifier, and the central frequency and bandwidth of the analogue band-pass filters, show a good match (within 1%) with the circuit simulations.With modulated light source and integrated lock-in detection the sensor effectively suppresses the interference from ambient light and 1/f noise.The single-chip sensor enables a compact and robust design solution that offers a route towards wearable devices for health monitoring.

View Article: PubMed Central - PubMed

Affiliation: Electrical System and Optics Research Division, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK. diwei.he@nottingham.ac.uk.

ABSTRACT
Pulse oximetry is a noninvasive and continuous method for monitoring the blood oxygen saturation level. This paper presents the design and testing of a single-chip pulse oximeter fabricated in a 0.35 µm CMOS process. The chip includes photodiode, transimpedance amplifier, analogue band-pass filters, analogue-to-digital converters, digital signal processor and LED timing control. The experimentally measured AC and DC characteristics of individual circuits including the DC output voltage of the transimpedance amplifier, transimpedance gain of the transimpedance amplifier, and the central frequency and bandwidth of the analogue band-pass filters, show a good match (within 1%) with the circuit simulations. With modulated light source and integrated lock-in detection the sensor effectively suppresses the interference from ambient light and 1/f noise. In a breath hold and release experiment the single chip sensor demonstrates consistent and comparable performance to commercial pulse oximetry devices with a mean of 1.2% difference. The single-chip sensor enables a compact and robust design solution that offers a route towards wearable devices for health monitoring.

No MeSH data available.


Related in: MedlinePlus

Second-order empirical calibration curve relating the absorbance ratio (R) from the CMOS sensor to the SpO2 level of the “BC biomedical FingerSim” phantoms in transmission mode.
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sensors-15-17076-f005: Second-order empirical calibration curve relating the absorbance ratio (R) from the CMOS sensor to the SpO2 level of the “BC biomedical FingerSim” phantoms in transmission mode.

Mentions: Deployment results of the full CMOS sensor in vitro to measure the equivalent SpO2 of the “BC biomedical FingerSim” phantoms in transmission geometry are shown in Figure 5. The measured R ratio values from the CMOS sensor for 97.5%, 90% and 80% SpO2 phantoms were 0.58, 0.92 and 1.15 respectively. To allow the ratio R to be related to the oxygen saturation over a wide range, a second order polynomial curve calculated from Matlab is used:SpO2 = 100.5 − 4.15 × R − 17.69 × R2(3)


A Single-Chip CMOS Pulse Oximeter with On-Chip Lock-In Detection.

He D, Morgan SP, Trachanis D, van Hese J, Drogoudis D, Fummi F, Stefanni F, Guarnieri V, Hayes-Gill BR - Sensors (Basel) (2015)

Second-order empirical calibration curve relating the absorbance ratio (R) from the CMOS sensor to the SpO2 level of the “BC biomedical FingerSim” phantoms in transmission mode.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4541923&req=5

sensors-15-17076-f005: Second-order empirical calibration curve relating the absorbance ratio (R) from the CMOS sensor to the SpO2 level of the “BC biomedical FingerSim” phantoms in transmission mode.
Mentions: Deployment results of the full CMOS sensor in vitro to measure the equivalent SpO2 of the “BC biomedical FingerSim” phantoms in transmission geometry are shown in Figure 5. The measured R ratio values from the CMOS sensor for 97.5%, 90% and 80% SpO2 phantoms were 0.58, 0.92 and 1.15 respectively. To allow the ratio R to be related to the oxygen saturation over a wide range, a second order polynomial curve calculated from Matlab is used:SpO2 = 100.5 − 4.15 × R − 17.69 × R2(3)

Bottom Line: The experimentally measured AC and DC characteristics of individual circuits including the DC output voltage of the transimpedance amplifier, transimpedance gain of the transimpedance amplifier, and the central frequency and bandwidth of the analogue band-pass filters, show a good match (within 1%) with the circuit simulations.With modulated light source and integrated lock-in detection the sensor effectively suppresses the interference from ambient light and 1/f noise.The single-chip sensor enables a compact and robust design solution that offers a route towards wearable devices for health monitoring.

View Article: PubMed Central - PubMed

Affiliation: Electrical System and Optics Research Division, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK. diwei.he@nottingham.ac.uk.

ABSTRACT
Pulse oximetry is a noninvasive and continuous method for monitoring the blood oxygen saturation level. This paper presents the design and testing of a single-chip pulse oximeter fabricated in a 0.35 µm CMOS process. The chip includes photodiode, transimpedance amplifier, analogue band-pass filters, analogue-to-digital converters, digital signal processor and LED timing control. The experimentally measured AC and DC characteristics of individual circuits including the DC output voltage of the transimpedance amplifier, transimpedance gain of the transimpedance amplifier, and the central frequency and bandwidth of the analogue band-pass filters, show a good match (within 1%) with the circuit simulations. With modulated light source and integrated lock-in detection the sensor effectively suppresses the interference from ambient light and 1/f noise. In a breath hold and release experiment the single chip sensor demonstrates consistent and comparable performance to commercial pulse oximetry devices with a mean of 1.2% difference. The single-chip sensor enables a compact and robust design solution that offers a route towards wearable devices for health monitoring.

No MeSH data available.


Related in: MedlinePlus