Asea Brown Boveri Ltd. (ABB) Award 2021 – Michael Graf

For his outstanding contributions in the area of integration and application of 2D material nanopores into biosensing and energy harvesting devices.

Solid-state nanopores are man-made, nano-sized openings in membranes separating two chambers containing a salt solution. When applying an electric field across the membrane, ions pass through the hole to get from one side of the membrane to the other. The isolation of mono-atomic crystals at the beginning of the 21st century sparked much interest in using 2D materials for nanopore devices. Monolayer MoS₂ not only provides a system with an ultimate low resistance to ionic current but also exhibits excellent ion-selectivity, making it the perfect ion selective membrane. This ion-selective behavior can be used to develop an energy-harvesting system based on the osmotic pressure. In nature, this energy can be extracted at places where rivers meet the ocean. Furthermore, the semiconducting membrane can be excited by light, potentially increasing the efficiency during daytime. Apart from generating energy, this 2D nanopore system can be used to detect biomolecules such as DNA. Thanks to the semiconducting property of the material, the classical ion detection can be complemented with a field-effect detection, able to sense the charge of a biomolecule during translocation. This thesis covers the fabrication of such membranes, as well as their application in energy generation and molecular sensing.