Enhanced Performance of an Electrochemical Sensor Using CNT Membrane for Accumulation-Based Detection of Nanoparticles

A carbon nanotube (CNT)-integrated microfluidic electrochemical sensor was developed for sensitive nanoparticle detection using gold nanoparticles (AuNPs) as the model analyte. The device incorporated screen-printed polyethylene terephthalate (PET) electrodes, a polydimethylsiloxane (PDMS) microchannel, and a CNT membrane that simultaneously served as a filtration layer and working electrode. This configuration enhanced analyte trapping, increased the electroactive surface area, and accelerated electron transfer under convective flow. The CNT membrane was fabricated by vacuum filtration and torch-assisted bonding, ensuring strong adhesion without adhesives or plasma treatment. Electrochemical analysis showed that the filter-integrated CNT sensor exhibited an oxidation current of 63 µA compared to 11 µA for the non-filter sensor, representing a fifteen-fold sensitivity enhancement. The detection limit improved from 1.0 × 10−3 to 7.5 × 10−4 mol·L−1 with excellent reproducibility (RSD < 5%) and ∼90% accuracy. These findings validated the filtration-assisted accumulation mechanism and demonstrated the effectiveness of CNT-integrated microfluidic sensors for enhanced nanoparticle detection, while highlighting their potential for future adaptation to biosensing applications.