Sensors - Hierarchical Nanostructures for Energy Devices - page 265

simultaneously. Consequently, the sensitivity of the sensor increases greatly
compared to the dense and compact counterparts of the same materials.
Furthermore, the response/recovery time of the sensor decreases consider-
ably since adsorption/desorption of gas onto the surface takes place very
quickly due to the diffusion-free behavior of the target analyte in hierarchical
nanostructures. By comparison, gas diffusion is very limited due to irregular
distribution of pore size and the highly serpentine pathway in the agglom-
erates of nanomaterials. For this reason, hierarchical nanostructure sensors
can be potent candidates for sensing biologically meaningful trace-level
molecules, ions, and biomarkers. In addition, they might find applications
in detecting toxins, hazardous gases and chemical and biological weapons
that need acute action to relieve the damage to human beings. However, the
mechanism by which hierarchical nanostructures are produced has not been
understood fully so that the desired structures are not easy to realize at
present. If the mechanism is clearly revealed, one can design appropriate
hierarchical nanostructure sensor platforms in a controllable way for target
analytes.

d n 3 r 4 n g | 4

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