Membrane sensitization biosensor based on magnetic inducing for Tau protein detection.

Surface stress-based biosensors exhibit excellent performance in detecting high concentrations of biomolecules; however, their sensitivity at low concentrations is often limited by insufficient deformation caused by weak binding-induced signals. To overcome this limitation, we propose an actively driven biosensor based on a multilayered heterogeneous magnetic film (PDMS/NiFe/FeMn), which achieves synergistic amplification of surface stress and geometric deformation under magnetic field modulation, thereby breaking through the sensitivity bottleneck of conventional designs. The sensor architecture leverages the high magnetic permeability of NiFe and the magnetostrictive effect of FeMn to construct a magneto-mechanical coupling interface: the NiFe layer efficiently transduces magnetic field energy, while the FeMn layer actively deforms to amplify the surface stress generated by target binding (Tau protein). A flexible PDMS substrate further releases mechanical strain, establishing a dual amplification mechanism of "biorecognition-magnetically driven deformation-electrical signal output." The experimental results show that the detection limit of this sensor for the Alzheimer's disease biomarker Tau protein is as low as 25.7 pM. Compared with self-made non-magnetic sensors, the sensitivity has been significantly improved, and it maintains stable performance in artificial cerebrospinal fluid. This approach, based on active signal amplification through heterogeneous magnetic film coupling, offers a new paradigm for the ultrasensitive detection of low-abundance biomarkers in complex biofluids and holds significant promise for the early diagnosis of neurodegenerative diseases.