Experimental Research on Welding of Front-end Stimulation Electrodes for Brain-Computer Interfaces

To address the high-reliability welding requirements of front-end stimulation electrodes for brain-computer interfaces (BCIs) in implantable medical applications, this study took platinum-iridium alloy (Pt90%, Ir10%) electrode assemblies as the research object and systematically compared the comprehensive performance of two mainstream processes, namely resistance spot welding and laser welding, in electrode connection. Through controlled variable experiments, the weld morphology, mechanical properties, and microstructure were systematically evaluated. The results showed that the welding strength of both processes exceeded the clinical threshold of 4N (8.9N for laser welding and 8.8N for resistance spot welding). The weld width of resistance spot welding (0.1–0.2mm) met the design requirements, while that of laser welding (0.3–0.5mm) was excessively large, which was prone to causing channel blockage. Microstructural analysis revealed that laser-welded joints had finer grains and no precipitated phases, whereas resistance spot welding achieved high hardness through grain refinement strengthening. In electrochemical tests, resistance spot-welded joints exhibited a lower corrosion current density and superior corrosion resistance. Combined with the analysis of welding mechanisms and evaluation of process stability, this research provides experimental evidence and engineering references for the optimal selection of welding processes for BCI electrodes in different clinical scenarios.