Orvostechnikai és biotechnikai műszaki tudományok és technológia
In this study, we developed and validated a single-shank silicon-based neural probe
with 128 closely-packed microelectrodes suitable for high-resolution extracellular
recordings. The 8-mm-long, 100-mu m-wide and 50-mu m-thick implantable shank of the
probe fabricated using a 013-mu m complementary metal-oxide-semiconductor (CMOS) metallization
technology contains square-shaped (20 x 20 mu m(2)), low-impedance (similar to 50
k Omega at 1 kHz) recording sites made of rough and porous titanium nitride which
are arranged in a 32 x 4 dense array with an inter-electrode pitch of 22.5 mu m. The
electrophysiological performance of the probe was tested in in vivo experiments by
implanting it acutely into neocortical areas of anesthetized animals (rats, mice and
cats). We recorded local field potentials, single- and multi-unit activity with superior
quality from all layers of the neocortex of the three animal models, even after reusing
the probe in multiple (> 10) experiments. The low-impedance electrodes monitored spiking
activity with high signal-to-noise ratio; the peak-to-peak amplitude of extracellularly
recorded action potentials of well-separable neurons ranged from 0.1 mV up to 1.1
mV. The high spatial sampling of neuronal activity made it possible to detect action
potentials of the same neuron on multiple, adjacent recording sites, allowing a more
reliable single unit isolation and the investigation of the spatio-temporal dynamics
of extracellular action potential waveforms in greater detail. Moreover, the probe
was developed with the specific goal to use it as a tool for the validation of electrophysiological
data recorded with high-channel-count, high-density neural probes comprising integrated
CMOS circuitry.
