Using electrical chemical impedance spectroscopy to determine nanocapillary geometry and differential capacitance by developing a variable topology network circuit model

Nanocapillaries find increasing use in a variety of applications including, protein translocation dynamics, protein sequencing, and other nanofluidic studies. All of these applications are affected by the geometry of the nanopore and the molecular species found within. This dissertation develops a new equivalent circuit model to determine the geometry of nanocapillaries. This model is derived to include the effects of a varying nanocapillary radius, along with the capacitive double layer within the nanocapillary. The model is tested by using electrochemical impedance spectroscopy on a nanocapillary array membrane. The resulting values extracted from the model fit are consistent with the manufacturer's specified geometry. The model is then further developed to determine the impedance of proteins. This is accomplished by modeling the protein as a cylinder and inserting this into our above mentioned model. By exploiting alternating regions of surface charge density on the protein this model will allow for the rapid sequencing of proteins.