The team from Beihang University has developed a super-resolution photonic force microscope, achieving sub-femtonewton mechanical sensing in aqueous solutions.

The team from Beihang University has recently developed a super-resolution photonic force microscope, achieving sub-femtonewton-level mechanical sensing in aqueous solutions for the first time. It detected the smallest electric field force at 108.2 aN, with a sensitivity of 1.8 fN/√Hz. This technology combines ion resonance nanoprobes, optical three-dimensional super-resolution positioning, and machine learning, addressing the challenge of weak force measurements in aqueous environments.

The applications of this microscope are extensive, particularly in studying extremely weak interactions between DNA molecules. Traditional theories suggest that complementary DNA strands require close contact to pair in aqueous solutions, but this new tool reveals the possibility of long-range forces. Additionally, the technology can be used to study interactions of molecules such as CRISPR proteins.

Detecting extremely weak forces in aqueous solutions is crucial for understanding the operation of biological molecules. Previously, the highest sensitivity for force measurements in aqueous solutions was about 10 fN/√Hz, but the new method has elevated this sensitivity to the sub-femtonewton level, providing an effective tool for studying long-range interactions of biological molecules in physiological environments.

Through theoretical analysis and experimental validation, the team improved force measurement accuracy by using lower potential well stiffness, higher positioning precision, and a large amount of positioning data. They also introduced a cylindrical lens positioning method from super-resolution imaging to refine the final steps of three-dimensional force measurement.

This research is not only scientifically significant but also opens new avenues for future studies on biological molecules.