2D Nanoflower-like MnO2-Modified Flexible Electrode with Compressive Strain-Enhanced Sensitivity for Reliable Cholesterol Monitoring

The development of flexible, high-performance electrochemical biosensors for continuous and on-site monitoring of cholesterol is critical for advancing cardiovascular health diagnostics and personalized medicine. Here, we present a flexible MnO₂-modified screen-printed electrode (MnO₂/SPE) for cholesterol detection, where two-dimensional flower-like MnO₂ nanomaterials are used to functionalize the electrode surface. The MnO₂ nanocomposite significantly improves the electrochemical performance of the SPE by reducing interfacial impedance, optimizing charge transfer kinetics, and providing abundant active sites for electrocatalytic oxidation. The MnO₂/SPE sensor exhibits excellent analytical performance, including a wide linear range (1–160 μM), a low limit of detection (0.16 μM), and a high sensitivity of 0.197 μA·μM⁻¹·cm⁻². Notably, compressive mechanical strain (-1%) is demonstrated to further boost the sensing performance via the flexoelectric polarization effect, increasing the sensitivity to 0.2497 μA·μM⁻¹·cm⁻² and accelerating the electrocatalytic oxidation of cholesterol. The MnO₂/SPE sensor also shows good stability, reproducibility, and anti-interference capability, with all relative deviations below 5%. This work provides a new strategy to enhance the performance of flexible electrochemical sensors through strain engineering and demonstrates great potential for wearable cholesterol monitoring.