MICROMACHINING OF A SILICON
MULTICHANNEL MICROPROBE
FOR NEURAL ELECTRICAL ACTIVITY RECORDING
Carmen Moldovan*, V. Ilian,
Ghe. Constantin, Rodica Iosub,
M. Modreanu, Ioana Dinoiu, B.Firtat, C. Voitincu
National Institute for
Research and Development in Microtechnologies, Center for
Microstructures and Microsystems for environmental and bio-medical
applications, P.O.Box 38-160, 023573 Bucharest, Romania
Abstract
The cellular potential
recording permits the investigation of the central nervous activity. The
paper presents the design and manufacturing steps of an 8-channel
microprobe for recording the electrical activity of neural cells and
tissues integrated on the same chip with the electronics. The specific
fabrication processes of the integrated microprobe are presented. An
implantable neural microprobe is developed to enable the correlation
between electrical activity in the human nervous system and externally
psycho-electrical
stimuli. The combination of bulk and surface silicon micromachining is
illustrated in a work on the simultaneous recording of spatially
separated activity from multiple neurons in the nervous systems /4/. The
extracellular potential recording permits the investigation of the
central nervous activity /4/. The low signal to noise ratio and the high
impedance signal transfer are important problems to be solved. The
multichannel microprobes were developed for exploring the organization
of the nervous system and for the development of close loop neural
prostheses.
As was demonstrated by
several research groups, silicon technology is presently a very good way
to produce multielectrodes with microscopic sizes, reproducible and good
mechanical and alectrical characteristics.
The width of the tip is 30
mm
for 4 channels and 60mm
for 8 channels microprobe. A unique channel probe is also prepared for
recording the electrical potential inside a cell in order to minimize
the mechanical damages due to the insertion in the cell and for
recording a living cell. In this case the width of the tip is 10mm.
The thickness of the tip is 20
mm for neural
insertion probe and 100
mm for muscular
insertion probe.