For gas sensors, the ultrasensitive and highly selective detection of multiple components is of great significance in a wide range of applications extending from environment to healthcare, which is still a long-term challenge due to the single sensing mechanism of most sensors. Here, we combine the advantages of microfluidic chips and surface-enhanced Raman spectroscopy (SERS) spectra to fabricate a smart single-chip for simultaneously detecting an arbitrary combination of VOCs that incorporates different detection units, working on either a physisorption or chemisorption mechanism. Full integration of microfluidic and multiplex nanostructure components on one chip permits programmable design for sensing multifarious volatile compounds, and enables on-chip signal amplifications with increased reproducibility. As a proof-of-principle experiment, we demonstrate the simultaneous identification of 9 different gases that belong to aromatic compounds, aldehydes, ketones, or sulfides in one mixture, with high sensitivity (ppb level), high selectivity, and high robustness (error ∼8%). We further evaluated the application of our universal gas sensor in two scenarios including indoor air pollution monitoring and exhaled breath-based disease diagnosis. We expect that our design will improve the various practical applications of gas sensors.
Keywords: Ti3C2Tx MXene; gas sensors; microfluidic chips; surface-enhanced Raman spectroscopy (SERS); volatile organic compounds (VOCs).