The Development of a Chemical Sensor for Low Temperature Hydrothermal Vent Sites: The Diffusive Properties of Teflon AF
The main goal of this internship was to study the diffusive properties of Teflon AF, a gas permeable membrane, in order to develop a chemical sensor that will be placed at low-temperature hydrothermal vent sites. Because low-temperature vent sites are abundant with biological life, the current sensors that exist are not capable of obtaining long term measurements of dissolved gases in the vent fluid as they become coated with a bio-film and are rendered useless. This internship explored the idea of encapsulating a sensor inside a highly permeable membrane that would resist biological buildup, thus enabling long term and continuous measurements of vent fluids.
Teflon AF (amorphous fluoropolymer) is an amorphous copolymer that is
extremely permeable due to poor inter-chain packing. To determine if the
Teflon membrane was sufficiently permeable for use in a sensor, studies
were conducted to determine the rate of diffusivity of CO2(aq). Also, the
permeability of another species of membrane, Teflon PTFE (polytetrafluoroethylene),
were tested and compared to those of Teflon AF. The study proved that although
the Teflon AF membrane was much more permeable than that of Teflon PTFE,
both membranes could potentially serve to encapsulate the sensor. Further
studies will explore the rates of diffusion for H2(aq) and also H2S(aq)
for both membranes. These studies will determine the most effective membrane
to be used in the construction of the new sensor to be placed at low-temperature
hydrothermal vents.