A Metamaterial Buckling-Assisted Surface-Acoustic-Wave Enabled Sensor (mBASES) for Versatile and Ultrasensitive Biomarker Detection.

Hydrogel metamaterials with programmable microarchitectures offer a promising route for converting molecular recognition into mechanical responses. However, efficiently transducing weak biomolecular perturbations into detectable signals without relying on molecular amplification remains a fundamental challenge. Here, we report a metamaterial Buckling-Assisted Surface-acoustic-wave Enabled Sensor (mBASES), which introduces a structure-triggered physical amplification mechanism by integrating bio-crosslinked hydrogel metamaterials with a surface acoustic wave (SAW) device. Through competitive biomolecular recognition, target binding induces hydrogel swelling that is engineered to match the critical buckling threshold of the metamaterial. This instability-enabled pattern transformation acts as an intrinsic mechanical gain element, converting weak molecular perturbations into amplified acoustic responses through coupled modulation of phononic transmission and hydrogel-SAW interactions. As a result, mBASES establishes a transduction pathway that links molecular recognition, hydrogel deformation, structural amplification, and ultimately acoustic readout. The platform enables rapid, label-free detection across multiple biomolecular classes, including proteins, nucleic acids, and metabolites. Clinical validation further demonstrates femtomolar-level detection of Herpes Simplex Virus (HSV) IgG and unamplified DNA in human serum within 5-15 min using a one-step assay. By amplifying the transduction process rather than the target molecules, mBASES establishes a versatile biosensing strategy, providing a promising platform for point-of-care diagnostics.