Liquid Metal-Enabled High-Robustness MEMS Flexible Neural Interface for Chronic Cortical Recording

This paper reports a wafer-scale-fabricated, flexible neural interface engineered to overcome the ubiquitous fracture failure of conventional Au-based interconnects under cyclic bending and physiological cortical micromotion. The device leverages ultra-dense, 2.1 µm-linewidth liquid metal (LM) interconnects patterned via a Phase-Transition Stress-Assisted Liquid Metal Film Densification (PTSA-LMFD) process, which enables MEMS-compatible high-resolution LM patterning. The resulting interconnects demonstrate exceptional mechanical resilience, withstanding multi-modal stresses—including 100 cycles of 180° bending, 180° twisting, or 10% stretching—without structural or functional degradation. Crucially, pre-folded devices subjected to 100 repeated 180° bending cycles maintain stable chronic electrophysiological recording after one-month cortical implantation, confirming unparalleled mechanical and operational robustness.