Interfacing Biomolecules, Cells and Tissues with Nanowire-based Electrical Devices - Applications of Electrochemistry and Nanotechnology in Biology and Medicine - page 87

Figure 6. Continuation. (C) (left) Top-down photograph of a heart located un-
derneath bent substrate with NWFETs on the lower concave face of the sub-
strate, which enables overall registration between heart and lithographically-
defined markers on the substrate. (right) Optical image taken with the same
system showing features on the heart surface versus position of individual
NW devices, which are located along the central horizontal axis. (bottom)
Recorded conductance data from a NWFET in this configuration.
face between the NWFETs and the beating heart, and highlight the
necessity of recording explicit device sensitivity to interpret corre-
sponding voltages. 41
As mentioned, the fabrication of NWs and CNT FETs on flex-
ible plastic substrates allows the entire chip to wrap the tissue and
increase the contact area with the recording elements ( Fig. 6A ,
right panel). Furthermore, it can be used for in vivo studies as
demonstrated in the case of polymer-based MEAs. 43 NWFETs
were assembled on 50-Pm thick flexible and transparent Kapton
substrates. To confirm the robustness of the measurements, the
heart was rotated 180° and a consistent inversion of signal was
observed. Secondly, the deformed conformation was investigated
by a bent device chip with concave surface facing a beating heart
immersed in medium, Fig. 6C . The Kapton is a flexible and trans-