Microfluidic Gel Chromatography-Enabled In-Situ Raman Spectroscopy for Selective Electronic-Type Separation and Analysis of Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWNTs) possess unique electronic properties—either metallic or semiconducting—defined by their chirality, making their selective separation a cornerstone for advancing nanotechnology applications. While conventional gel chromatography has proven effective for large-scale separation, the demand for microscale precision to uncover nanoscale interaction mechanisms and optimize separation strategies remains unmet. In this study, we report the development of a polydimethylsiloxane (PDMS)-based microfluidic platform integrating gel chromatography with in-situ Raman spectroscopy to achieve high-resolution electronic-type separation of SWNTs. By systematically isolating metallic- and semiconducting-enriched fractions (M1-M3, S1-S3), our approach leverages real-time Raman spectroscopy to reveal dynamic shifts in G-band characteristics and G⁻/G⁺ intensity ratios, providing quantitative insights into separation efficiency and purity. The platform’s novel integration of rate constant analysis and SDS concentration normalization highlights the inherent elution kinetics of SWNTs, with metallic SWNTs exhibiting accelerated separation dynamics compared to their semiconducting counterparts. This advancement not only enhances the resolution of electronic-type differentiation but also underscores the critical role of dispersant concentration in fine-tuning separation outcomes. The results establish this PDMS microchannel system as a versatile and scalable solution, bridging the gap between industrial-scale separations and microscale precision, paving the way for cutting-edge nanomaterial purification technologies.