Magnetoelastic resonators improve humidity sensing capabilities, wirelessly

Humidity detection is important for various applications, from biodetection and biosensing to control of industrial processes, including advanced microelectronics fabrication and indoor air quality monitoring, the latter of which was crucial during the Covid-19 pandemic.

While recent research has consistently focused on improving humidity sensors, a vast majority of the devices require electrical connections to carry signals from transducer elements to processing units.

Sisniega et al. introduced the use of magnetoelastic resonance (MER) sensors in conjunction with metal-organic frameworks (MOFs) to develop an effective wireless tool for real-time humidity detection.

“What was in our minds was the possibility of developing a remote humidity sensor that did not need electrical connections and could be innovative and quite useful for some applications, for example, in those where the sensor must operate in hermetic, closed, or hardly accessible spaces,” said author Beatriz Sisniega.

Because the resonators, which can detect changes on the mass loading of its surface, require water absorption capacity, the researchers incorporated hygroscopic MOF layers into them.

Throughout the study, the team analyzed the water adsorption behavior of five different MOF materials and their performance once integrated into the MER sensors, showing that the sensors performed successfully for humidity detection, with high selectivity to water molecules, sensitivity, stability, precision, and competent response times. They also revealed that the MOF materials bestow the sensors with remarkable operational versatility.

“The ability of MER sensors to operate contactless combined with the exceptional adsorption capacity and the selectivity of MOF materials may open the door to a new generation of contactless gas sensors,” said Sisniega.

Source: “Magnetoelastic resonators functionalized with metal-organic framework water harvesters as wireless humidity sensors,” by Beatriz Sisniega, Roberto Fernández de Luis, Jon Gutiérrez, and Alfredo García-Arribas, APL Materials (2024). The article can be accessed at https://doi.org/10.1063/5.0206165 .