Study of nanopipettes conductivity depending on their shape and size

Жуков М.В., Лукашенко С.Ю. Исследование проводимости нанопипеток в зависимости от их формы и размеров // Научно-технический вестник информационных технологий, механики и оптики. 2026. Т. 26, № 2. С. 258–265. doi: 10.17586/2226-1494-2026-26-2-258-265

There is increasing interest in research on glass pipettes with micro- and nanoscale outlets which are used for non-destructive morphology studies of native biological objects in liquids, biosensors, and 3D printing. The shape and size of pipettes have a decisive influence on their ionic conductivity and mechanical stability, which directly impacts the results of measurements using them. This study examines ionic conductivity with changes in the shape and size of pipettes produced under different formation conditions. The effect of nonlinear ion current conductivity on high-aspect-ratio nanopipettes with outlet sizes of about 100 nm or less was discovered and studied. Glass pipettes are formed by heating and subsequent axial stretching of the capillaries under mechanical load. The shape and size of the formed pipettes are determined using a scanning electron microscope. The pipette surface is coated with a thin layer of Au using magnetron sputtering to improve their visibility in the electron microscope. Ionic conductivity and pipette outlet diameter are measured using voltammetry. The dependence of ionic conductivity changes on the shape and size of glass pipettes was obtained by varying thermal pulling parameters. Thermal pulling parameters were determined that ensure the formation of conical and high-aspect-ratio nanopipettes with 100–200 nm outlet and 3–8° convergence angles at the apex, used in scanning capillary microscopy. Pipettes with 500–1000 nm outlet and 3–5° convergence angles, used in the patch-clamp method, were obtained. Cases of nonlinear conductivity with different Ion Current Rectification Coefficients, arising when using high-aspect-ratio nanopipettes with ionic conductivity resistances of approximately 50–100 MΩ, were studied. The obtained results will enable the formation of pipettes with a given conductivity, shape, and size as well as the consideration of the effects of nonlinear conductivity of high-aspect-ratio nanopipettes in such areas as scanning capillary microscopy, the patch-clamp method, micro- and nanovolume injection of substances into cells, nanobiopsy, and capillary 3D printing

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