Dual-Readout Self-Resetting CMOS Image Sensor for Resolving Sub-Percent Optical Contrast in Biomedical Imaging

TL;DR

A new CMOS image sensor improves biomedical imaging by detecting very small optical contrast changes with high precision.

Contribution

The dual-readout self-resetting CMOS sensor enables sub-percent contrast resolution with high SNR, overcoming reset artifacts.

Findings

The sensor achieves over 70 dB SNR, near the shot-noise limit.

It successfully visualized ±0.25% contrast fluctuations in vascular phantom experiments.

The design allows continuous data acquisition during self-reset periods.

Abstract

We report a dual-readout self-resetting CMOS image sensor that achieves a signal-to-noise ratio (SNR) exceeding 70 dB and resolves sub-percent optical contrast variations by effectivly suppressing reset artifacts. The proposed sensor employs a Dual-Readout architecture with two independent scanners operating with a temporal offset; while one readout system is in the self-reset “dead time”, the other remains active, thereby physically ensuring continuous data acquisition. To minimize pixel area while achieving high reconstruction accuracy, a minimum frame-to-frame difference algorithm is utilized for signal restoration without requiring in-pixel counters. A prototype chip fabricated in a 0.35-μm process demonstrated SNR characteristics near the shot-noise limit, with a peak SNR exceeding 70 dB. Vascular phantom experiments using a carbon black suspension successfully visualized ±0.25% contrast fluctuations—dynamic signals previously undetectable by conventional sensors. This device provides a powerful platform for high-precision bio-imaging applications, including brain surface blood flow monitoring, where both wide dynamic range and high SNR are essential.

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