Investigating the potential of using gold nanoparticle-functionalized micromechanical sensors for gamma radiation detection

Highlights: • AuNP-modified micromechanical sensors was demonstrated for detecting γ radiations. • XRD shows that average grain size of the AuNPs increased in response to γ radiations. • MEMS sensors show a great potential for detecting other types of radiations. Herein, we investigate the potential of using gold nanoparticle (AuNP)-functionalized microcantilever surfaces for gamma radiation detection. For this investigation, Si microelectromechanical system-based cantilevers and Si wafers are used. All the samples were irradiated using a⁶⁰Co gamma source at different radiation doses (kGy). Using scanning electron microscopy, energy-dispersive X-ray and X-ray diffraction (XRD) spectroscopies, the optical properties of Si microcantilevers coated with AuNPs were studied before and after the irradiation. Atomic force microscopy (AFM) was used to determine the resonance frequency shift due to the usage of AuNPs as sensing layers on microcantilevers. The results demonstrated that Au nanosphere (50 and 100 nm) suspensions in water were successfully deposited on Si substrates via dropping deposition without requiring any chemical material. Clearly, the XRD patterns of the AuNPs coated onto the Si substrates had the same peaks before and after the irradiation; however, after gamma irradiation, all the peaks become more distinct. As per AFM, the responses of the 50-nm AuNP-coated sensors were highly sensitive and almost linear at radiation doses between 0 and 20 kGy, unlike the 100-nm AuNP-coated sensors, which did not exhibit any consistent response. This study constitutes a foundation for the development of a portable and cost-effective platform for the sensitive detection of nuclear radiations using micromechanical sensors.