IMEC paves way for multi-electrode deep-brain stimulation
24 April 2009
The Belgium-based Interuniversity Microelectronics Centre (IMEC) has
presented a new design strategy for brain implants, which it used to
create a prototype multi-electrode stimulation and recording probe for
deep-brain stimulation. With this development, IMEC has highlighted the
opportunities in the healthcare market for design tool developers.
Brain implants for electrical stimulation of specific brain areas are
used as a last-resort therapy for brain disorders such as Parkinson's
disease, tremor, or obsessive-compulsive disorder. Today’s deep-brain
stimulation probes use millimeter-size electrodes. These stimulate, in a
highly unfocused way, a large area of the brain and have significant
unwanted side effects.
Wolfgang Eberle, Senior Scientist and project manager at IMEC’s
bioelectronics research group said: “To have a more precise stimulation
and recording, we need electrodes that are as small as individual brain
cells (neurons). Such small electrodes can be made with semiconductor
process technology, appropriate design tools, and advanced electronic
signal processing. At DATE, we want to bring this message to the design
community, showing the huge opportunities that the healthcare sector
offers.”
IMEC’s design and modelling strategy allows developing advanced brain
implants consisting of multiple electrodes enabling simultaneous
stimulation and recording. This strategy was used to create prototype
probes with 10 micrometer-size electrodes and various electrode
topologies.
The design strategy relies on finite-element modelling of the
electrical field distribution around the brain probe. This was done with
the multi-physics simulation software COMSOL 3.4 and 3.5. The COMSOL
tools also enabled investigating the mechanical properties of the probe
during surgical insertion and the effects of temperature.
The results indicate that adapting the penetration depth and field
asymmetry allow steering the electrical field around the probe. This
results in high-precision stimulation. Also key to the design approach
is developing a mixed-signal compensation scheme enabling
multi-electrode probes capable of stimulation as well as recording. This
is needed to realize closed-loop systems.
These new design approaches open up possibilities for more effective
stimulation with less side effects, reduced energy consumption due to
focusing the stimulation current on the desired brain target, and
closed-loop control adapting the stimulation based on the recorded
effect.
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