Ti₃C₂T_x MXene-Loaded 3D Substrate toward On-Chip Multi-Gas Sensing with Surface-Enhanced Raman Spectroscopy (SERS) Barcode Readout

Abstract

Gas sensors lie at the heart of various fields ranging from medical to environmental sciences, and the demand of gas sensors is instantly expanding. However, in the face of complex gas samples, how to maintain high sensitivity while performing multiplex detection still puzzles the researchers. Here, by introducing Ti 3 C 2 T x MXene into a microfluidic gas sensor with a three-dimensional (3D) transferable SERS substrate, a powerful gas sensor having both multiplex detecting ability and high sensitivity is demonstrated. The employ of MXene endows the sensor with a universal high adsorption efficiency for various gases while the generation of in situ gas vortices in the sophisticated nanomicro structure extends the molecule residence time in SERS-active area, both leading to the increased sensitivity. In the proof-of-concept experiment, a limit of detection (LOD) of 10−50 ppb was achieved for three typical volatile organic compounds (VOCs) according to the intrinsic SERS signals of gas molecules. Besides, the welldesigned periodic 3D structure solves the general repeatability problem of SERS substrates. In addition, the detailed composition of gas mixture was revealed using classic least-square analysis (CLS) with an average accuracy of 90.6%. Further, a chromatic barcode was developed based on the results of CLS to read out the complex composition of samples visually. KEYWORDS: surface-enhanced Raman spectroscopy (SERS), volatile organic compounds (VOCs), self-assembly, MXene, Ti 3 C 2 T x , classic least-square analysis (CLS)

A Family of 2D-MXenes: Synthesis, Properties, and Gas Sensing Applications

“…For instance, Zhu et al designed a flexible Ti 3 C 2 T x MXene-based microfluidic gas sensor on a three-dimensional (3D) transferrable SERS (surface-enhanced Raman spectroscopy) microfluidic chip for multiplex gas sensing. 229 The presence of in situ gas vortices results in an extension of molecule residence time in the SERS-active area and improved sensing performance. The detection of multiplex VOCs was possible by the SERS-Vortexene sensor because the SERS technique has the capabilities of fingerprint spectra, as shown in Figure 8(i).…”

“…The presence of a target gas in the environment affects the electrical properties of an interface material, such as its relative permittivity or conductivity, resulting in measurable changes The reported MXene-based gas sensors are mainly based on resistance type (chemiresistors), and presently the detection limit has reached the ppb level. 182,184,185,191,193 Apart from various MXene-based chemiresistive array sensors that have been successfully developed to identify and simultaneously detect multiplex gases, recent advancements in SERS 229 and planar microwave resonator-based sensors showed promising results, 230 which can accurately identify multiplex compounds by single acquisition. Nevertheless, the MXenes-based chemiresistive gas sensors are in their early stages; there are numerous challenges to overcome before revealing the commercial prospects of these sensors.…”

Two-dimensional MXenes: recent emerging applications

“…In recent years, different MXenes like Ti 3 C 2 T x , 16,17,169–175 Ti 3 C 2 , 176–178 Ti 2 CT x , 179 V 4 C 3 T x , 180,181 and Mo 2 CT x 182,183 are utilised for the recognition of different gases, volatile organic compounds (VOCs), and humidity. Due to its exceptional characteristics, Ti 3 C 2 T x is the most extensively used MXene as a gas sensing material.…”

SERS-Enabled Sensitive Detection of Plant Volatile Biomarker Methyl Salicylate

“…The SERS intensity and frequency of these probe molecules can be affected by other molecules which have chemical and/or physical interaction with them. Thus, they can be used to detect other molecules which do not have a large Raman cross section or strong interaction with the plasmonic structures. − In this work, we adopted this strategy and developed a SERS sensor for MeSA vapor detection. Specifically, 4-mercaptophenylboronic acid (MPBA) functionalized AuNPs were employed as the SERS probe.…”