Biomedical Engineering Reference
In-Depth Information
Pushing the limits of PDMS/cell displacement experiments close
to but below the point of cell disruption yielded peaks with aver-
age conductance amplitude of 299 ± 7 nS and corresponding cali-
brated signal amplitudes as large as 10.5 ± 0.2 mV. In comparison
to previous studies, cardiomyocytes cultured on conventional pla-
nar FET devices have yielded peaks with S/N of 2-6 and ampli-
tudes from 0.2-2.5 mV, which highlight this approach and the high
performance of the Si-NWFET devices used.
Lastly, multiplexed measurements of NWFET devices were
carried out and configured in a linear array with an average spac-
ing of 300 Pm so that signal propagation within the cardiomyocyte
monolayers could be characterized. Simultaneous recordings from
three NW devices in contact with spontaneously beating monolay-
er ( Fig. 7k-l ) yielded very stable and high S/N (~10) peaks. Using
the individually characterized sensitivities for each NW, calibrated
voltages with relative large magnitude of 4.6 ± 0.4, 4.0 ± 0.3 and
5.9 ± 0.9 mV were obtained, indicating that a good junction is
formed between each of the NWFETs and PDMS/cell substrate in
the experiment. These results and device separations yield approx-
imate propagation speeds of 0.07-0.21 m/s that are consistent with
measurements on monolayers of neonatal rat cardiomyocytes. 45b
VII. NANOSCALE 3D-FLEXIBLE FET BIOPROBES
The studies reviewed here demonstrate that NW electrical devices,
fabricated on rigid or flexible planar substrates, can be used for
ultrasensitive detection of biological markers and high-resolution
extracellular recording from cells and tissues with relevance to
healthcare and medicine. However, localized and tunable 3D intra-
cellular recording using nanoscale field-effect transistor devices, in
a similar manner to glass micropipette, has never been demonstrat-
ed before. 46 The design of minimally-invasive nanoFET probe for
intracellular recording applications is a significant fabrication chal-
lenge because the S (source) and D (Drain) typically dominate the
overall device size and define a planar and rigid structure regard-
less of whether the nanoFET is on or suspended above a
substrate. 47 Nevertheless, this kind of nanoFET could function as
mechanically non-invasive probe capable of entering cells through
endocytic pathways in a similar manner to nanoparticles. 48 Moreo-
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