An Ultrahigh-Frequency and Highly Sensitive Acoustic Wave Biosensor with an Au/Monolayer MoS ₂ /LiNbO ₃ Structure for Alpha-Fetoprotein Detection

This work successfully developed a horizontal shear wave mode surface acoustic wave (SH-SAW) biosensor based on a monolayer of molybdenum disulfide (MoS₂) on a lithium niobate (LN) substrate for ultrahigh-sensitivity detection of alpha-fetoprotein (AFP) in serum. Operating at approximately 1.91 GHz, this sensor marks the first use of such a high frequency in biosensing, reducing detection time from hours to minutes and significantly improving mass sensitivity. Its device structure also demonstrates excellent potential for miniaturization and integration. Experimental results demonstrate a limit of detection (LOD) as low as 3.29 pg/mL for AFP, substantially enhancing sensitivity. The sensor exhibits a linear detection range from 1 pg/mL to 100 ng/mL, along with excellent specificity and stability. This work provides a crucial technical pathway for constructing high-performance, chip-level integrated portable detection platforms, offering broad application prospects in precision medicine and point-of-care diagnostics.