Modeling Mechanical Interactions at Nanostructured Hemo/Tissue-Electrode Interfaces: Balancing Surface Area and Structural Robustness

To advance biosensors for in vivo biomonitoring, incorporating nanostructures can enhance electrode surface area and signal detection. However, fabricating such nanostructured electrodes often compromises surface mechanical robustness, particularly under insertion forces or physiological motion. Nanoporous gold (np-Au) electrodes, with interconnected nanoscale pores, exhibit improved mechanical strength over nanodendritic surfaces, though the mechanisms behind this are not fully understood. We present a multiphysics simulation model to study mechanical interactions between nanostructured electrodes and surrounding blood/tissue under physiological conditions. The model includes both extroverted (protruding) and introverted (inset) nanostructures with varying geometries and surface dimensions. Laminar flow with different rates and viscosities mimics biomechanical forces from biomotion. Simulations reveal that extroverted structures experience high stress concentrations at the base as height increases, increasing the risk of structural failure. In contrast, introverted designs maintain mechanical stability across geometries, making them more suitable for durable, high-surface-area interfaces. Experimental data validate these trends. This work provides design guidelines for optimizing nanostructured electrode interfaces, offering a framework to balance surface area enhancement with mechanical robustness for reliable in vivo biosensing.