Biomimetic nanopores from atomically thin membranes
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Biological cells are filled with a variety of pores and channels that transport ions and molecules across the cell membrane. These passageways are vital to cell function and remarkably effective due to their high selectivity, high flux, and sensitivity to environmental stimuli. This level of control is extremely attractive for applications ranging from biotechnology to energy and the environment. In this thesis, the unique properties of two dimensional materials are utilized to create solid-state nanopores that closely mimic the function of biological ion channels. Ionic conductance measurements were used to demonstrate that nanopores introduced into graphene membranes exhibit K+/Na+ selectivity and can modulate the ionic current with an applied gate voltage. These devices are shown to respond to low gate voltages (<500 mV) at biologically relevant concentrations (up to 1M). Cation-anion selectivity, concentration dependence, and pH dependence were also investigated. We propose the observed behavior is dependent on the presence of surface adsorbates that modify the surface energy of the membrane and near the pore, creating a gaseous barrier that is modulated via electro-wetting. Additionally, we work toward creating light responsive MoS2 nanopores operating in solution, by monitoring the current through a MoS2 nanopore while the device is exposed to a focused laser beam.