Researchers reveal graphene’s variable transparency to van der Waals forces

Understanding how atomically thin materials transmit or screen intermolecular forces, particularly vdW interactions, is crucial for developing nanofluidic and microelectromechanical systems. Although previous experiments have investigated this phenomenon, results have been contradictory, leaving uncertainty over whether materials like graphene behave as transparent transmitters or as barriers to vdW forces. To address this, the research team used colloidal atomic force microscopy (AFM), a precision technique that measures adhesion and attractive forces through a microsphere-tipped cantilever probe. Their experiments, performed under ultra-dry conditions, compared graphene supported on silicon dioxide (SiO₂) substrates with graphene suspended across microcavities. Two complementary measurement modes – pull-off and pull-in tests – enabled them to quantify the extent to which substrate forces pass through or are screened by graphene layers.

Researchers from China’s Peking University, Nanjing University of Aeronautics and Astronautics and Tsinghua University have gained new insights into the van der Waals (vdW) transparency of graphene, a property that determines how it mediates molecular interactions at the nanoscale.Understanding how atomically thin materials transmit or screen intermolecular forces, particularly vdW interactions, is crucial for developing nanofluidic and microelectromechanical systems. Although previous experiments have investigated this phenomenon, results have been contradictory, leaving uncertainty over whether materials like graphene behave as transparent transmitters or as barriers to vdW forces. To address this, the research team used colloidal atomic force microscopy (AFM), a precision technique that measures adhesion and attractive forces through a microsphere-tipped cantilever probe. Their experiments, performed under ultra-dry conditions, compared graphene supported on silicon dioxide (SiO₂) substrates with graphene suspended across microcavities. Two complementary measurement modes – pull-off and pull-in tests – enabled them to quantify the extent to which substrate forces pass through or are screened by graphene layers.

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