Periodic Reporting for period 4 - AngstroCAP (Fundamental and Applied Science using Two Dimensional Angstrom-scale capillaries)
Reporting period: 2024-08-01 to 2025-09-30
The ANGSTROCAP project delves into the confined matter utilizing Ångstrom (Å)-scale channels with atomically smooth walls. This architecture of capillaries provides tunability of capillary dimensions, ensuring a level of atomic-scale precision and smoothness previously unattainable. Despite the atomic scale, our top-down lithographic technique guarantees high reproducibility and flexibility, making these channels a versatile tool for a wide range of applications. The AngstroCAP project utilized angstrom-scale capillary devices to investigate the confined water. These devices are in a lab-on-a-chip type configuration with angstrom-scale channels and atomically smooth walls. The project assembled capillaries of a few microns in length, by sandwiching two blocks of layered crystals, separated by an atomically thin 2D-crystal spacer stripes. Inside these channels, the water flows were investigated along with that of water-salt solutions. We studied size selective sieving of ions and molecules using these channels to probe ion selectivity mechanisms from a fundamental science perspective.
Simultaneously, AngstroCAP investigates gas flows in atomic scale confinement. Gas flows in angstrom-scale constrictions are of significant importance for gas extraction and separation processes. In the case of extremely narrow pores which are much smaller than the mean free diffusion path of gas molecules, the gas flows can be described by conventional Knudsen theory. Here, the diffusing molecules randomly bounce back or scatter from the walls of the pores rather than colliding with each other. Until now, researchers didn’t know at which scale the Knudsen description would break down. We have shown that it holds true, even at the ultimate atomic limit. Our method is simple and robust for quantification of pores through gas flows and can be used for molecular-separation, sensing and monitoring gases and in single quantum-emitters.
The overall objectives of the AngstroCAP project are two-fold
Objective 1: To utilize angstrom-scale capillaries constructed out of two-dimensional (2D) materials as a versatile platform for studying confinement effect on water and ions.
Objective 2: To construct new types of angstrom-scale 2D-pores from these capillaries for studying gas flows, volatile organic molecule adsorption, biomolecular translocation.
Simultaneously, AngstroCAP investigates gas flows in atomic scale confinement. Gas flows in angstrom-scale constrictions are of significant importance for gas extraction and separation processes. In the case of extremely narrow pores which are much smaller than the mean free diffusion path of gas molecules, the gas flows can be described by conventional Knudsen theory. Here, the diffusing molecules randomly bounce back or scatter from the walls of the pores rather than colliding with each other. Until now, researchers didn’t know at which scale the Knudsen description would break down. We have shown that it holds true, even at the ultimate atomic limit. Our method is simple and robust for quantification of pores through gas flows and can be used for molecular-separation, sensing and monitoring gases and in single quantum-emitters.
The overall objectives of the AngstroCAP project are two-fold
Objective 1: To utilize angstrom-scale capillaries constructed out of two-dimensional (2D) materials as a versatile platform for studying confinement effect on water and ions.
Objective 2: To construct new types of angstrom-scale 2D-pores from these capillaries for studying gas flows, volatile organic molecule adsorption, biomolecular translocation.
The AngstroCAP project team, have progressed and completed successfully all of the work packages of the project.
We have successfully optimised fabrication methods of angstrom capillaries and fabricated several devices, while improving the design by various trial and feedback from characterized devices (WP1 and WP2). One review article (Annual Review of Materials Research 2022), perspective has been published along with one protocol methods paper (Nature Protocols 2024). We have made significant progress in developing the new method of making 2D pores by using microtomy (Advanced Functional Materials 2024). The initial months were dedicated to training and developing protocols for the methods. Following this, we have experimented with several 2D-materials’ slicing, and the results are published as a manuscript. We have used these sliced channels for biomolecular translocation (Nanoscale 2025) as well as for hydrogen evolution reaction (ACS Nano 2025).
We studied hydrocarbons and gas flows through angstrom capillaries (Science Advances 2020) and an invited article from the team is published in “emerging investigators collection” of RSC Nanoscience journal.
In terms of outputs: 20 peer-reviewed journal publications with the ERC grant acknowledged.
The PI and the team have attended several conferences and workshops (some virtually and several in-person) with PI and team members giving talks. A few to name are 2D TMD 2025 and ICAMD 2025 (PI Invited talks), Nanofluidics 2024 (PI invited talk), ICMAT 2023 (team member contributed talk), EMLG/JMLG conference 2022 (Invited lecture PI, team member contributed talk), Materials Research Society Fall meeting 2022 (Invited lecture x2), Pacifichem 2021 (Young giants in Nanoscience, invited lecture), Liquid Matter 2021 (plenary lecture), International Winter school on Electronic Properties of Novel Materials (2020, invited lecture of PI, 2023 poster presentations from 3 team members), RSC Faraday online symposia 2020 (award lecture), World Laureates Forum 2020 (Invited lecture), CENT-MIT seminar series 2020 (invited lecture).
We have successfully optimised fabrication methods of angstrom capillaries and fabricated several devices, while improving the design by various trial and feedback from characterized devices (WP1 and WP2). One review article (Annual Review of Materials Research 2022), perspective has been published along with one protocol methods paper (Nature Protocols 2024). We have made significant progress in developing the new method of making 2D pores by using microtomy (Advanced Functional Materials 2024). The initial months were dedicated to training and developing protocols for the methods. Following this, we have experimented with several 2D-materials’ slicing, and the results are published as a manuscript. We have used these sliced channels for biomolecular translocation (Nanoscale 2025) as well as for hydrogen evolution reaction (ACS Nano 2025).
We studied hydrocarbons and gas flows through angstrom capillaries (Science Advances 2020) and an invited article from the team is published in “emerging investigators collection” of RSC Nanoscience journal.
In terms of outputs: 20 peer-reviewed journal publications with the ERC grant acknowledged.
The PI and the team have attended several conferences and workshops (some virtually and several in-person) with PI and team members giving talks. A few to name are 2D TMD 2025 and ICAMD 2025 (PI Invited talks), Nanofluidics 2024 (PI invited talk), ICMAT 2023 (team member contributed talk), EMLG/JMLG conference 2022 (Invited lecture PI, team member contributed talk), Materials Research Society Fall meeting 2022 (Invited lecture x2), Pacifichem 2021 (Young giants in Nanoscience, invited lecture), Liquid Matter 2021 (plenary lecture), International Winter school on Electronic Properties of Novel Materials (2020, invited lecture of PI, 2023 poster presentations from 3 team members), RSC Faraday online symposia 2020 (award lecture), World Laureates Forum 2020 (Invited lecture), CENT-MIT seminar series 2020 (invited lecture).
The AngstroCAP grant team members have made several original contributions, significantly extended the capabilities of nanofluidics beyond the state of the art, combining diverse materials and unconventional fabrication methods. Membrane-based applications such as osmotic power generation, desalination and molecular separation would benefit from decreasing water friction in nanoscale channels. However, mechanisms that allow fast water flows are not fully understood yet. The AngstroCAP team reported that angstrom-scale capillaries made from atomically flat crystals and study the effect of confining walls’ material on water friction (Nature Communications 2021). A massive difference is observed between channels made from isostructural graphite and hexagonal boron nitride, which is attributed to different electrostatic and chemical interactions at the solid-liquid interface. Our team in collaboration with Prof Bocquet's group (ENS Paris, France), we have reported neuromorphic memory using Å-channels, where electrolytes in 2D nanochannels develop long-term memory, from tens of minutes to hours (Science 2023).
In collaboration with Prof Radenovic's group (EPFL, Switzerland), we probed the 2D-confinement on organic liquids, where native defects on hBN act as nanoscale probes with super-resolution microscopy (Nature Materials 2023). We have extended further our collaboration with in-situ microscopy of electrical deformation induced ionic memory within 2D channels (in communication with journal, 2026).
Theoretically, four different types of memristors are possible, differentiated by their hysteresis loop direction (Nature communications 2025). We showed that by varying electrolyte composition, pH, applied voltage frequency, channel material and height, all four memristor types can emerge in nanofluidic systems. We observed two hitherto unidentified memristor types in 2D nanochannels and investigated their molecular origins. A minimal mathematical model incorporating ion–ion interactions, surface charge, and channel entrance depletion successfully reproduces the observed memristive behaviors. We further investigated the impact of temperature on ionic mobility and memristors characteristics. We showed that the channels display both volatile and non-volatile memory, including short-term depression akin to synapses, with signal recovery over time. These results suggest that nanofluidic devices may enable new neuromorphic architectures for pattern recognition and adaptive information processing.
In collaboration with Prof Radenovic's group (EPFL, Switzerland), we probed the 2D-confinement on organic liquids, where native defects on hBN act as nanoscale probes with super-resolution microscopy (Nature Materials 2023). We have extended further our collaboration with in-situ microscopy of electrical deformation induced ionic memory within 2D channels (in communication with journal, 2026).
Theoretically, four different types of memristors are possible, differentiated by their hysteresis loop direction (Nature communications 2025). We showed that by varying electrolyte composition, pH, applied voltage frequency, channel material and height, all four memristor types can emerge in nanofluidic systems. We observed two hitherto unidentified memristor types in 2D nanochannels and investigated their molecular origins. A minimal mathematical model incorporating ion–ion interactions, surface charge, and channel entrance depletion successfully reproduces the observed memristive behaviors. We further investigated the impact of temperature on ionic mobility and memristors characteristics. We showed that the channels display both volatile and non-volatile memory, including short-term depression akin to synapses, with signal recovery over time. These results suggest that nanofluidic devices may enable new neuromorphic architectures for pattern recognition and adaptive information processing.