Xth International Seminar on Inclusion Compounds (ISIC

1
Xth International Seminar on Inclusion Compounds
(ISIC10) September 1923, 2005 Kazan, Russia
Materials
Device
Polyacrylnitril (PAN) fiber with diameter from 20
up to 40 nanometers (Fig.1.)
We have constructed a precise device for the
measurement of electric resistance of polymeric
fibers. It is based on the FemtoScan scanning
probe microscope and reveals several advantages
experiments can be performed in the environmental
chamber using different adsorbates and at various
temperatures. The temperature inside the chamber
is controlled by thermistor, which acts also as a
heater. The device allows to observe adsorption
of different gases by the microfiber and to find
its dependency upon temperature.
Fig.3. Scheme of the device. 1 - operational
amplifier and container with sample, 2-
digital-to-analog converter and analog-to-digital
converter, 3 - DSP-card, 4 server and client
computers
Fig.2. Picture of Polyacrylnytryl fibres made by
electron microscope.
The dependence of the conductivity of PAN upon
temperature and humidity of air is found
irreversible changes of a fiber conductivity are
registered during the electrical current passage
Fig.4. Container with sample. Also on this figure
you can observe termistor, special magnets for
holding the sample and holes for sorbate.
Fig.6. The change of electrical conductivity with
temperature in open atmosphere. Temperature
varies from 20 to 60 degrees centigrade.
Resistance varies from 2750 to 3860 Om.
Electrical conductivity
Fig.5. Measurement of electrical noise.
Current-voltage relation.
Temperature (time)
The device can measure the resistance of fibers
with accuracy 0.5, i.e. 20-100 Om depending on
fiber resistance.
Fig.7. Current-voltage relation of
Polyacrylnitril fiber.
Conclusion The application of the device for the
studying gas-hydrates is proposed. It is possible
to watch for adsorption by tracing changes of
electrical resistance. The device can be used as
a main part of the chemical sensor for the
measurements of adsorption.
The support of the Russian Foundation for Basic
Research (project N 04-03-32472) and Russian
Academy of Sciences (Program Chemistry and
physchemistry of supramolecular systems and
atomic clusters) is acknowledged.