Magnetic anisotropic membrane-based mechanical biosensor for sensitization enhancement

Abstract

Mechanical biosensors based on surface stress present a novel paradigm for the detection of biological molecules. However, the sensitivity improvement of the mechanical biosensor remains a significant challenge. Herein, a magnetic-sensitization mechanical biosensor based on stress-electric conversion was proposed to enhance the hemoglobin (HB) detection performance. To achieve this, the magnetic anisotropic PDMS membrane with the Fe3O4 nanoparticles chain-like structures was employed as the sensitive element of the biosensors. Benefiting from the super-paramagnetic property and magnetization retention of the membrane, the biosensor obtained a pre-strain in a magnetic field to overcome membrane gravity. The biosensor received signal amplification, resulting in greater membrane deformation due to the surface stress. The HB detection associated with hematological disease serve as a proof of concept indicating the enhanced sensitivity. The limit of detection (LOD) for HB was calculated as 42.91ng/mL, which was lower by 1 order of magnitude than that at the isotropic biosensor. The successful and accurate testing of clinical blood samples also revealed the reliability of the biosensor. The detection results of HB demonstrated the key role of anisotropic magnetic thin films to the sensitivity improvement of mechanical biosensors, and provided a new strategy for early diagnosis of blood diseases.