Development of SAW sensors coated with metal organic framework and borophene for detection of Covid-19

Abstract

The rapid and accurate detection of COVID-19 biomarkers is critical for the early diagnosis and effective treatment of the disease. In this study, surface acoustic wave (SAW) biosensors coated with metal-organic framework (MOF) and borophene layers were developed to detect COVID-19 biomarker gases, including isopropyl alcohol, n-butyraldehyde, acetone, and ethyl butyrate. In addition, the gas measurement system includes ethanol and n-hexane, which are already present in human exhaled air. The objective of this study is to investigate the response of different MOFs and borophene to these biomarker gases and to determine the optimal sensing material for COVID-19 biomarker detection. Seven different materials are coated onto SAW sensors using the drop-casting method as sensing layer. These materials include borophene, MIL-101 (Fe), MIL-101 (Fe)-Borophene, MIL-125, MIL-125-Borophene, MOF-5, and MOF-5-Borophene. They are selected based on their distinct metal components and their potential for detecting COVID-19 biomarker gases. When choosing MOFs, it is preferred to use MOFs that have same organic ligand but a different metal in their center. It is aimed at comparing metal effects and other results related to metal effects. Sensing molecules are characterized using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and Brunauer-Emmett-Teller (BET) analysis. SEM is employed for analyzing the thickness and roughness of coating films on SAW sensors. To examine the sensor's frequency change, a gas measurement system in TÜBİTAK MAM is employed. This system is for the preparation of gas mixtures at different concentrations and humidity levels, which are then sent to the surface of the sensors at room temperature with a constant flow rate. In addition to measuring the change in resonance frequency of the transducer device, the electrical conductivity of the surface is simultaneously measured under related gases to determine the influence of electrical conductivity on sensor performance. Results are processed using MATLAB to read, compare, and perform principal component analysis (PCA). The results of the gas sensing experiments show that the MOFs have a better response to the COVID-19 biomarker without borophene. MOFs also exhibited good selectivity for the target gases. This suggests that these sensors could be used for selective detection of COVID-19 biomarkers in a mixed environment. Keywords:surface acoustic wave(SAW) sensors, metal organic frameworks (MOFs), volatile organic compounds(VOCs), biomarkers, COVID-19