Interfacing Biomolecules, Cells and Tissues with Nanowire-based Electrical Devices - Applications of Electrochemistry and Nanotechnology in Biology and Medicine - page 81

tential signals were elicited and recorded either by a conventional
glass microelectrode impaled in the soma or by NW electrodes
interfaced with an axon or dendrite.
Various set-ups of device structures were designed, for in-
stance, a repeating 1-neuron/1-nanowire motif with the soma and
the axon directed across the respective nanowire element. The re-
sults show the direct temporal correlation between the intracellular
spikes initiated and recorded in the soma and the corresponding
conductance peaks measured by the nanowire at the axon nanowire
junction, Fig. 4B . For a p-type NW, an action potential will result
in enhanced conductance followed by reduced conductance (the
relative potential at the outer membrane becomes more negative
and then more positive). Also, stimulation with the NW at the
NW/axon junction resulted in somatic action potential spikes,
which were detected with the intracellular electrode.
In this work it was shown that nanowire devices can be used
to stimulate, inhibit, or reversibly block signal propagation along
specific pathways while simultaneously following the signal flow
throughout the network, capabilities that current techniques are not
able to.
Following this work, other groups reported on the effective
electrical interfacing between nanowire-based devices and bioelec-
trical cells. 40
In a later work, reported in 2010, Si NWFET arrays were used
for mapping neural circuits in the brain, 40a Fig. 5A . Neural circuits
are organized into hierarchical networks operating on spatial and
temporal scales that span multiple orders of magnitude. 40d It is
highly desirable to map the activities in large populations of neu-
rons with high position accuracy and precise timing. Revealing the
functional connectivity in natural neuronal networks is central to
understanding circuits in the brain. It was shown that silicon nan-
owire field-effect transistor (Si NWFET) arrays fabricated on
transparent substrates can be reliably interfaced to acute brain slic-
es. Devices were readily designed to record across a wide-range of
length scales. Simultaneous NWFET and patch clamp studies ena-
bled unambiguous identification of action potential signals, with
signal amplitudes of 0.3 to 3 mV, Fig. 5B .
These results demonstrate that the NWFET arrays detect local
activity of the pyramidal cell layer and lateral olfactory tract on at
least the 10-Pm scale, and thus can be used to understand the func-