Fabrication and characterization of the flexible neural microprobes with improved structural design

The fabrication method and the characteristics of a new generation of intracortical microprobes with improved structural design are presented. These devices are integrated with flexible interconnection cable and provide enough mechanical strength for penetration into the tissue. Gold micro-needles are embedded in the probe shanks to locally reinforce the implants. The microprobes offer an array of electrodes with 32 recording channels located on 4 parallel shanks with 2, 4, and 8-mm lengths. The impedance characteristics and stability of electrodes were studied in acidic and saline solutions. To reduce the channel impedance and enhance the signal to noise ratio, iridium was electroplated on the gold electrode sites. Stable electrical characteristics of both iridium and gold electrodes were demonstrated over the courses of prolonged pulse stress tests for 100 million cycles. The functionality of fabricated microprobes was confirmed by successful recording of the local field potential from intact mouse hippocampus.