Rhombic-magnetoelastic/metal-organic framework functionalized resonators for highly sensitive toluene detection

The monitoring of different harmful gases such as volatile organic compounds (VOCs) is essential to ensure the air quality and population security. Therefore, the development of rapid, cheap and accurate sensing devices is a key to enable continuous monitoring of the air quality. On this matter, magnetoelastic sensors, particularly the rhombus-shaped ones, have become an interesting alternative to the current sensing systems because, besides exhibiting a fast response, they present a wireless sensing capacity. Moreover, the addition of metal-organic frameworks (MOFs) as highly porous active layers to different sensing devices endows them with the desired adsorption capacity and selectivity to detect VOCs. Therefore, in this work, we explore the performance of a highly sensitive rhombic magnetoelastic Metglas 2826 MB resonator functionalized with a high-toluene adsorption capacity MOF layer ( i.e. UiO66-NH 2 ) for its wireless detection. Our findings confirm the feasibility of the Metglas/MOF system for fast and reversible toluene detection, being key the control of the active layer mass to improve its sensitivity. From the toluene sensing experiments, a maximum sensitivity of 0.27 Hz ppm −1 was determined. Finally, the sensor selectivity has been evaluated through the analysis of the sensor response to different atmospheres (water, acetone, ethanol and toluene) and it was observed that the sensor presents an enhanced selectivity towards toluene. Given the structural diversity and chemical tunability of MOF materials, their use as active sorbent layers in resonator systems together with the possibility to further optimize the resonator geometry to improve the sensitivity and the MOF structure to gain more selectivity, opens up the possibility for the facile and straightforward designing of future wireless sensors for any kind of environmentally hazardous substance. Rhombic magnetoelastic sensors functionalized with MOFs have been applied for the wireless sensing of VOCs showing very promising results.