Toward a CMOS-integrated quantum diamond biosensor based on NV centers

TL;DR

This paper presents a progress report on developing a CMOS-integrated quantum diamond biosensor using NV centers, aiming for compact, scalable magnetic imaging in biological settings.

Contribution

It introduces a CMOS-integrated platform combining NV centers with a custom SPAD array, enabling practical, scalable quantum biosensing.

Findings

Estimated magnetic field sensitivity of ~90 nT/√Hz per pixel.

Analysis of system design for biological compatibility and scalability.

Feasibility of resolving ODMR shifts with sub-μT sensitivity.

Abstract

We report progress toward a CMOS-integrated quantum diamond biosensing platform that combines nitrogen-vacancy (NV) centers in diamond with a custom 40 nm CMOS Single-Photon Avalanche Diode (SPAD) array. The system integrates on-chip active quenching and digital readout with external FPGA-based photon counting, compact microwave delivery, and practical optical excitation and collection schemes to support widefield optically detected magnetic resonance (ODMR). System-level design considerations spanning fluorescence collection efficiency, detector count-rate capability, and microwave homogeneity are analyzed with biological compatibility and scalability in mind. Using superparamagnetic iron oxide nanoparticle (SPION)-labeled HEK293T cells as a representative use case, simple dipole-field estimates indicate that sub-$\mu$T sensitivity is required to resolve ODMR shifts within typical ensemble linewidths. Based on the proposed architecture and efficiency analysis, a magnetic field sensitivity of approximately 90 nT/$\sqrt{\mathrm{Hz}}$ per pixel is estimated. These results outline a practical path from optics-heavy quantum diamond microscopes toward compact, CMOS-integrated NV-based biosensors for quantitative magnetic imaging in complex biological environments.