Dual-Mode SAW Biosensor With Rayleigh Mixing and Love Wave for Enhanced Cancer Biomarker Detection in Plasma

This study presents a dual-mode surface acoustic wave (SAW) biosensor on a single piezoelectric platform that integrates Rayleigh wave-based acoustic mixing with waveguided Love mode SAW detection for real-time, label-free sensing of a cancer biomarker, carcinoembryonic antigen (CEA). The Love wave sensor features a noise-cancelling delay line to effectively remove environmental noise and thermal drift from acousto-thermal heating during Rayleigh wave mixing. The optimized waveguide layer has demonstrated improved acoustic energy confinement and reduced insertion loss. For the immunosorbent assay, Rayleigh wave mixing significantly enhances analyte transport in viscous environments, such as human plasma, reducing diffusion limitations from a static liquid sample and accelerating antigen–antibody binding. Comparative studies between phosphate-buffered saline (PBS) and plasma samples show that SAW mixing effectively improves phase response and reduces saturation times across the CEA concentration range. The platform achieved a lower detection limit of 4.68 ng/mL in plasma with SAW mixing compared to 8.16 ng/mL without mixing. These findings demonstrate the potential of combining Rayleigh and SH-SAW modes for reduced assay time, improved biosensor sensitivity, and robustness in complex biofluids.