The conventional brain–machine interface (BMI) concept is based on an
electrical circuit that includes electrodes for sensing and/or
stimulation. In most cases, electrodes are in contact with biological
tissue, while the electrical circuit can be positioned on the backside of
electrodes or connected through a wireless link [1–3]. In both cases,
a tremendous amount of work is done to design a high-sensitivity circuit to
detect a few millivolts related to electrical signal propagation in the
brain [4, 5].
With recent advances in microfabrication and processing, more advanced
systems can be considered to build a BMI [6–8]. Following these major
advances, the highly integrated lab-on-a-chip (LoC) emerged, which led to
the design of compact LoC in the size range of a few millimeters [9, 10].
LoC has become attractive as an advanced brain–machine interface and
a promising approach for future new brain discoveries.
Conventional brain–machine interfaces: deep brain electrode
stimulation
There are two major operations that are handled by BMI, which are stimulation
and sensing. Conventional BMIs are deep brain electrodes (DBE) or patch
electrodes [11, 12] used to detect the electrical activity of the brain. In
the stimulation mode, DBE applies voltages or currents to tissue to generate
action potentials (AP). In the sensingmode electrodes are used to detect the
propagation of AP and brain electrical activity.