A further design for a gas sensor applying platinum bars as electrical contacts is
shown in Figure 2.15. Although this design avoids the response-delaying conductive
surface layer, the electrical path through the sensing particles is significantly longer.
However, it would be relatively straightforward to implement this design in a chip.
Figure 2.13 Comparative response over time of two gas sensors utilizing a conventional material
with grain size either in the micrometer or nanometer range ( www.boulder.nist.gov/div853/
Publication%20files/NIST_BCC_Nano_Hooker_2002.pdf ).
Figure 2.14 Gas sensor following the design
principle shown in Figure 2.12 (Cho and Hahn,
TU Darmstadt, private communication). The
titania-sensing particles are placed on a gold
electrode and the top electrode is gas
permeable (this is clearly visible in the image at
the right-hand side of the figure).
Figure 2.15 Sensor design applying platinum
bars as electrical contacts. The sensing
nanoparticles (e.g., SnO 2 ) are located between
these contacts. The molecules to be detected
(in this example oxygen and CO) are shaded
dark and light gray, respectively. (Note the
molecules and nanoparticles are not drawn to
the same scale.)
2.2 Elementary Consequences of Small Particle Size j17
shown in Figure 2.15. Although this design avoids the response-delaying conductive
surface layer, the electrical path through the sensing particles is significantly longer.
However, it would be relatively straightforward to implement this design in a chip.
Figure 2.13 Comparative response over time of two gas sensors utilizing a conventional material
with grain size either in the micrometer or nanometer range ( www.boulder.nist.gov/div853/
Publication%20files/NIST_BCC_Nano_Hooker_2002.pdf ).
Figure 2.14 Gas sensor following the design
principle shown in Figure 2.12 (Cho and Hahn,
TU Darmstadt, private communication). The
titania-sensing particles are placed on a gold
electrode and the top electrode is gas
permeable (this is clearly visible in the image at
the right-hand side of the figure).
Figure 2.15 Sensor design applying platinum
bars as electrical contacts. The sensing
nanoparticles (e.g., SnO 2 ) are located between
these contacts. The molecules to be detected
(in this example oxygen and CO) are shaded
dark and light gray, respectively. (Note the
molecules and nanoparticles are not drawn to
the same scale.)
2.2 Elementary Consequences of Small Particle Size j17