Charge Transport and Electrical Switching in Composite Biopolymers - Biomaterials: Physics and Chemistry - page 241

Degree of localization of the carriers in the trap states is indicated by γ R >1 which shows
that the charges are highly localized. Table 3 also shows that when the temperature
decreases, the average hopping energy W decreases and the average hopping distance R
increases, supporting the fact that when the phonon energy is insufficient (low
temperature), carriers will tend to hop larger distances in order to locate in sites which are
energetically closer than their nearest neighbours.
6. Conclusion
Current-Voltage characteristics of the cuticles, as a function of irradiation, annealing, and
temperature, show electrical switching with memory effect. The threshold voltage increases
with irradiation time and annealing temperature but it decreases with increase in
measurement temperature. The threshold voltage of the annealed and irradiated samples
ranges between 6-8 volts. Electrrical conduction in the OFF state follows Ohms' law but
changes to space charge limited current after switching to ON state. A combination of
Fowler-Nordheim field emission process and redox processes are responsible for electrical
switching of the samples. Conduction at low temperatures takes place by variable range
hopping mechanism. Since this biomaterial is biodegradable and is also considered to be
biocompatible and immunologically inert, it has high potential in biomedical applications. It
can be used in making contact eye lenses, scaffolds in tissue engineering, and in controlled
release of drugs. Most notably, due to its switching properties, its use in the design of
biosensors utilizing ion channels is very feasible.
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