Biomedical Engineering Reference
In-Depth Information
FIgURE 7.2:
Hardware block diagram for a closed-loop BMI.
(25 kHz sampling and 12 bits for action potentials, and with 300 Hz with 12 bits for LFPs). Figure
7.2
shows a more detailed block diagram of a closed-loop BMI, where the most important parts are
clearly detailed: the electrodes (signal sensing), the amplification, the signal processing (both at the
preprocessing and the interpretation), the wireless telemetry, the robotic interface, and the feedback
to the user.
We will present two basic approaches for portable BMIs, one short term and another more
long term. These approaches will be called first- and second-generation BMI systems.
Generation 1 is a “backpack” approach allowing some mobility to the animal or human pa-
tient. Several research groups are working on designs that fall into this category with one or two
commercial products in the market. The degrees of freedom (materials, geometries, amplification,
A/D, wireless) to accommodate the experimentalist and engineering are enormous, and are visible
on the very different engineering solutions proposed and implemented by many research groups
[
8-23
]. Because continuous operation for many hours is a necessity, several modes of operation are
possible with the available electrodes and headstages [
24
,
25
]:
