Microfluidics-Guided Assembly of Fluorescent Nanodiamonds for Temperature Mapping of a Cell Aggregate

We present a microfluidics-guided assembly method to fabricate fluorescent nanodiamond (FND) clusters with controlled morphology on various substrates. The assembled clusters exhibited enhanced fluorescence intensity and improved signal-to-noise ratio, enabling subkelvin sensitivity in the temperature measurements. Integrated into a microfluidic device, these clusters enabled real-time temperature mapping of a cultured cell aggregate with single-cell spatial resolution. Upon chemical stimulation, localized thermal responses were detected, reflecting cellular metabolic activity. This approach offers a platform for thermometry in biological systems and holds promise for applications in organ-on-a-chip technologies and micrometer-scale thermal analysis.