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

Area of Science:

• Biomedical Engineering
• Integrated Circuit Design
• Wearable Technology

Background:

• Pulse oximetry is crucial for noninvasive blood oxygen saturation monitoring.
• Existing devices can be bulky and susceptible to interference.
• Need for compact, robust, and accurate oximetry solutions for continuous health monitoring.

Purpose of the Study:

• To design and test a single-chip pulse oximeter using CMOS technology.
• To integrate essential components for signal acquisition and processing onto a single chip.
• To evaluate the performance and accuracy of the developed single-chip sensor.

Main Methods:

• Fabrication of a single-chip pulse oximeter in a 0.35 µm CMOS process.
• Integration of photodiode, transimpedance amplifier, filters, ADCs, and DSP.
• Utilized modulated light source and lock-in detection for noise suppression.
• Performance evaluation through breath-hold experiments compared to commercial devices.

Main Results:

• Circuit simulations showed excellent agreement (within 1%) with experimental measurements.
• The integrated sensor effectively suppressed ambient light and 1/f noise.
• Demonstrated comparable performance to commercial pulse oximeters with a mean difference of 1.2%.

Conclusions:

• The single-chip pulse oximeter offers a compact and robust design.
• This integrated solution facilitates the development of advanced wearable health monitoring devices.
• The technology shows significant potential for widespread adoption in personal health tracking.