Bioresorbable Mo–W Electrodes: Toward an Extended Operational Lifetime Through Controlled Alloying and Oxide Coating Engineering

ABSTRACT Bioresorbable metals and oxides are central to developing active transient implants, but their exposure to harsh biofluids challenges long‐term functionality due to ongoing dissolution. Biodegradable metal alloys have been proposed to improve corrosion resistance, though research has mainly focused on passive systems based on Mg, Zn, and Fe. Even though Mo and W exhibit superior corrosion resistance and gradual biodissolution among resorbable metals, their application as active sensing materials remains largely unexplored. This work presents a pioneering investigation into the electrochemical stability and sensing performance of Mo–W thin film electrodes. A key factor contributing to the unique stability of alloys is their ability to form stable passivating films which mitigate galvanic interactions. The self‐healing properties of these layers further enhance the electrode's durability. In this work we demonstrate that a nanometre‐thin crystalline WO _x coating significantly enhances the electrochemical stability of Mo–W‐based electrodes and enables reliable oxygen (−9.0 ± 0.2 µA/%O ₂ ) and pH (−33.0 ± 0.2 mV/pH) sensing for up to 10 days in simulated body conditions. Our findings establish Mo and W mixtures with an engineered surface oxide coating as a highly promising avenue for extending the operational lifetimes of bioresorbable implants, an essential step forward toward achieving clinical applicability.