Surface Engineering of Metal–Organic Framework Prepared on Film Bulk Acoustic Resonator for Vapor Detection

Abstract

Gravimetric resonators based on micro/nanoelectromechanical systems (M/NEMS) are potential candidates in developing smaller, less expensive, and higher-performance gas sensors. Metal−organic frameworks (MOFs) with high surface areas have recently come into focus as advanced nanoporous sensitive materials in microgravimetric gas sensors. The surface of MOFs on those sensors is critical in offering water stability and varying absorption behaviors. However, the influences of the surface on sensing performance are less explored and the strategy to tune surface properties of MOFs mounted on gravimetric resonators is still rare. In this paper, a straightforward strategy to engineer surface properties of M OFs, specifi cally Cu 3 (benzenetricarboxylate) 2 (known as HKUST-1), is reported and the surface hydrophilicity/hydrophobicity of HKUST-1 is tuned by chemical vapor deposition combined with monolayer self-assembly. It was found that the hybrid inorganic and organic surface engineering strategy not only preserves the absorption capacity of inner MOFs but also significantly enhances the sensor's stability toward water.

Two-Dimensional MoS2 for Resonant-Gravimetric Detection of Ppb-Level Formaldehyde

“…The proportion of S 6+ in 1T-MoS 2 is also larger than that in 2H-MoS 2 , which proves that a part of S 2– in 1T-MoS 2 has been oxidized to SO 4. − The deconvolution of XPS peaks of the 1T phase reveals the composition of the 1T phase in 1T-MoS 2 is about 70.4% . We also tested the BET surface area of the two materials and their nitrogen adsorption/desorption curves, which are shown in Figure d.…”

“…To date, gravimetric gas sensors (GGSs) have attracted tremendous research interest due to their low working temperature, great chemical and thermal stability, and simple working mechanism . Based on different working principles, GGSs can be further divided into quartz crystal microbalance (QCM), surface acoustic wave (SAW), and resonant microcantilevers.…”

Metal‐Organic Framework Based Gas Sensors

“…The microresonators are typically fabricated using clean-room technologies involving multi-step processing, including photolithography. [35,123] In an initial study conducted by Yaghi, Candler, and co-workers, [123] ZIF-69 coated microresonator sensors were fabricated by dropcasting the preformed MOF crystals onto the center paddle of the resonators. The frequency shift of the resultant resonators was substantially increased by around 78 times compared to that of the bare microresonator.…”

“…Recent progress on the successful implementation of MOFs onto versatile solid-state surfaces [21] propelled the development of MOF-based devices, for example, electrically-transduced gas sensors (chemiresistor, capacitors, FETs, mass-sensitive, and electrochemical sensors), memristors, interferometers, and micro-ring/surface plasmon resonators. [5][6][7][8][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] The MOF-based gas sensors outstand in the following aspects. [39] First, the permanent porosity of MOFs offers a large specific surface area and potential active sites (e.g., coordinatively unsaturated open metal sites and terminated functional groups) that are beneficial to elevated gas uptake and transportation.…”

The Role of Metal–Organic Frameworks in Electronic Sensors

“…reported a chiral MOF (Zn 2 (bdc)(L‐lac)(dmf)⋅DMF) as the sensing layer of a coated QCM sensor for the discrimination of enantiomers. Yan et al [43h] . engineered the surface hydrophilicity/hydrophobicity of MOFs with polydimethylsiloxane (PDMS) and monolayer self‐assembly.…”