Interfacing Biomolecules, Cells and Tissues with Nanowire-based Electrical Devices - Applications of Electrochemistry and Nanotechnology in Biology and Medicine - page 78

to their specific antibody, are flowed into the sensing compartment
where the sensing events occur on the nanoribbon-based devices.
However, this sensing platform requires the use of a pair of anti-
bodies against each biomarker of interest, one during the purifica-
tion capturing step and one during the sensing step. Additionally,
the use of silicon nanoribbons limited the detection sensitivity of
the platform to ~1 ng/mL.
IV. NANOWIRE FET ARRAYS FOR THE ELECTRICAL
MONITORING OF SINGLE NEURON AND NEURAL
CIRCUITS
Previous studies provided strong support that NW and CNT devic-
es have substantially higher sensitivity than planar FETs and thus
can offer advantages for cellular recording beyond other technolo-
gies available today. Methods for measuring the electrical activity
produced by electroactive cells include techniques such as glass
micropipette electrodes, 26 voltage sensitive dyes, 26c multi electrode
arrays (MEAs) 27 and planar FETs, 28 which have and continue to
play an important role in understanding the electrical behavior of
individual cells and cellular networks. 29b Micropipette electrodes
can stimulate and record extracellular potentials in vitro and in
vivo but more importantly, it can measure intracellular potentials
with relatively good spatial resolution, 29b,30 capability that the other
technologies still cannot reach. Yet, this method is invasive and
especially difficult to multiplex where multiple recordings from
different neurons are intended. Extracellular recordings are nonin-
vasive and allow recording from multiple sites, from both individ-
ual cells and neural networks, 29,31 but suffer from very low signal-
to-noise (S/N) ratio because of the use of relatively large elec-
trodes and their imprecise positioning relative to the cell. 31
Nanotechnogy-based devices are particularly attractive for in-
terfacing with neurons since they are compatible with the size of
neuron projections, and are able to detect and stimulate cellular
activity at the level of individual axons or dendrites. A unique in-
trinsic feature of these devices compared with conventional planar
devices is that the nanodevices protrude from the plane of the sub-
strate, and hence can increase NW/cell interfacial coupling, form-
ing naturally tighter junctions with the local cell membrane.