Biomedical Engineering Reference
In-Depth Information
10.0
9.5
9.5
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
Modulus from nanoindentation
Parallel mixing model
Guth's theory
0
2
4
6
8
10
CB vol %
Figure 9.4
Young's Modulus of SU-8/CB composite as a function of CB Vol %. Here all
the samples were indented with Pmax = 450 mN [27].
with two existing theories for particulate i lled polymer nanocomposites
with spherical i llers [38, 39].
Electrical characterization of SU-8/CB nanocomposites was carried
out to understand the conduction behaviour of the nanocomposite at
dif erent CB loading and i nd out the usable range of concentrations
of CB in SU8. For this, SU-8/CB resistors of varying CB concentration
with gold contacts were fabricated. Current voltage (I-V) characteris-
tics of SU-8/CB resistors with dif erent CB i ller loadings were analysed.
I-V characteristics of samples with lower concentration samples exhib-
ited symmetric and a non-ohmic behaviour and the characteristics tend
to become linear for samples with i ller loading well above percolation
threshold[25]. Figure shows IV characteristics for SU-8/CB composites
with 4.9 CB vol. % and 9.4 CB vol. %. h e I-V characteristics for dif er-
ent CB concentrations were found to i t well with theoretical model that
explains the conduction behaviour of nanocomposites as tunnelling of
electrons from one particle to next particle inside the polymer matrix.
h e tunnelling of electrons through the gaps separating the carbon
aggregates can reasonably justify the observation of translation of non-
ohmic to nearly ohmic (quasi-ohmic) behaviours in IV characteristics
with increase in CB vol%[27].
h e nanocomposite resistors were also characterized to investigate the
variability in the resistance values. It was observed that the percentage
