CMOS-Based High-Density Silicon Microprobe Array for Electronic Depth Control in Neural Recording

This paper reports on a novel CMOS-based high-density silicon microprobe array for intracortical recording applications. In contrast to existing systems, CMOS multiplexing units are integrated on the slender, needle-like probe shaft 160 μm in width. In the present implementation an unequaled number of 188 electrodes (diameter 20 μm, pitch 40 μm) are arranged in two columns along the 4-mm-long probe shaft. The on-shaft integration of electronics is motivated by the requirement to discriminate single action potentials in extracellular recordings necessitating a close proximity between the neuron of interest and the recording electrode. Instead of a mechanical movement of the probe shaft carrying the electrode, the position adjustment during long-term recordings is performed by switching between different electrodes arranged in a dense array. The paper presents the probe concept, the post-CMOS fabrication process and initial measurements evaluating electrode impedance and probe performance during measurements in saline solution.