Technique improves solid-state nanopores

Cells naturally exchange materials with their surroundings through nanoscale holes in the cell membrane. While nanopores could be powerful tools for monitoring single biomolecules in a solution, biological pores are limited by their size. It is also difficult to integrate devices into the pores that can be mass produced in a semiconductor facility. To compensate, scientists are working to develop solid-state nanopores using synthetic materials.

St. Denis et al. have developed a new technology using an atomic force microscopic (AFM) tip that can form a nanopore in a synthetic membrane. This technology easily allows for the combination of multiple pore sensors as well as detectors, electronic circuitry or tiny micro-nanochannels.

“The ability to integrate multiple pores will make it possible to build a large range of new nanopore device types,” said co-author Walter Reisner. “Tip-controlled local breakdown can produce very small, less than 5 nanometer, pores at precise positions, allowing for fabrication of multiple pores exactly where they are needed.”

The researchers used a voltage pulse at the tip to form a pore by a process termed dielectric breakdown. An Arduino-based circuit turns the voltage off once the membrane had been ruptured, controlling final pore diameter. The AFM tip also allows the researchers to map and follow the natural topography, like microwells, within the membrane when creating pores.

The researchers confirm their proof-of-concept design and demonstrate how it can be used to create smaller, more controlled holes in a synthetic membrane compared to current methods on the market. They are working with their commercial partner, Norcada, to make the technique available to the scientific community.

Source: “An apparatus based on an atomic force microscope for implementing tip-controlled local breakdown,” by T. St-Denis, K. Yazda, X. Capaldi, J. Bustamante, M. Safari, Y. Miyahara, Y. Zhang, P. H. Grutter, and W. Reisner, Review of Scientific Instruments (2019). The article can be accessed at https://doi.org/10.1063/1.5129665 .