Biomedical Engineering Reference
In-Depth Information
Fig.5(c) shows I-V curves of the cuticles obtained at different poling/measurement. These
curves show that electrical current increases as measurement temperature increase. This is
due to thermal excitation of the trapped charges across the potential barrier. The curves also
show that forward bias characteristics have two regions which are typical examples of
ohmic conduction for voltages below
V
th
(OFF-state) and a space charge limited current
(SCLC) for voltages above
V
th
(ON-state).
.
Increase in temperature facilitates diffusion of
ions in the space charge polarization. Thermal energy may also aid in overcoming the
activation barrier for orientation of polar molecules in the direction of the field. Charge
carrier generation and transport in mitochondrial lipoprotein system has been investigated
by electrical conductivity and the results show that increase in temperature causes a
transition in conductivity where steady state conduction is correlated with chain segmental
reorientations of phospholipid moiety below the transition and with an interfacial
polarization process above it (Eley et al., 1977).
Fig. 5. I-V curves of the pristine cuticles and cuticles treated at different conditions. (a)
pristine & samples pre-annealed at 320K and 400K for 12hrs each. (b) pristine & samples
pre- irradiated with laser light of wavelength 632.8nm for the duration shown in the
legends.(c) pristine samples measured at different temperatures. The insets in (a), (b) and (c)
show variation of threshold voltage as a function of the annealing temperature, irradiation
time, and measurement temperature respectively. (d) shows combined curves with the
conditions shown in the legends.
V
th
rapidly decreases with the increase in measurement temperature and that switching and
memory effect almost disappears at higher temperatures (370K). This is due to the fact that
the
V
th
decreases and that the gap between current in the forward bias and reverse bias in
the ON-state region almost closed up such that the forward bias current nearly folllows the
same path as the reverse bias current which indicates a loss of memory.
