Maskless Digital Fabrication of Implantable Flexible Neural Probes for High‐Fidelity Single‐Neuron Recording

ABSTRACT Rapid customization of implantable flexible neural probes remains constrained by conventional cleanroom microfabrication. Here, we present a fully maskless manufacturing strategy that integrates aerosol jet printing (AJP) with femtosecond‐laser micromachining. Commercial 6–8 µm polyimide (PI) films serve as ultrathin substrates; AJP directly defines Au interconnects and PI insulation, while femtosecond‐laser processing shapes the probe geometry and insertion‐guiding hole. Across three fabrication batches (n = 30 probes), the process produces 21.23 ± 0.79 µm‐wide Au traces with an absolute Au–PI registration error of 1.29 ± 0.78 µm, demonstrating reproducible multilayer fabrication. The printed Au microelectrodes exhibit a cathodic charge storage capacity of 10.43 mC cm − 2 and an impedance of 152.4 ± 54.5 kΩ at 1 kHz. Acute recordings in rat hippocampal CA1 enable extracellular spike detection and isolation of five single units. In a 30‐probe small‐batch benchmark, the workflow reduces hands‐on time by 43.5%, minimum sequential fabrication time by 65.0%, and quantified facility‐plus‐material cost by 59.7–60.9% relative to a representative cleanroom process. This digitally reconfigurable strategy provides a complementary route for rapid prototyping, small‐batch production, and iterative customization of implantable neural probes.