Current Research

Introduction: The Xu research lab develops and applies highly-integrated SPM-based technologies to study single molecule electronic, mechanical, and interaction properties, establishing molecular structur-functionality relationaships and how environmental factors contribute to such properties.



  • Ultrahigh resolution imaging in liquids;



Single molecule recognition imaging, kinetics and dynamics;

Controlling electronic transport in single molecule junction devices;

SPM nanolithography



  • Highly Integrated Methods Development: Develop and optimize highly integrated methods to combine Scanning Probe Microscope (SPM) nanolithography, microscopes (SPM and inverted optical microscope), SPM spectroscopy and SPM-based breakjuction methods to study single molecular electronic and mechanic properties and single molecule detection and recognition in biosystems.




  • SPM Bioimaging and Molecular Nanolithography: Define molecular nanopatterns for imaging and single molecular electronics study.




  • Molecular Nanoelectronics: Basic issues of electronic transport on the nanoscale are fairly well understood in systems such as semiconductor quantum wires and point contacts, metallic point contacts, and even in molecular systems like single walled carbon nanotubes. However, the same is far from true for organic molecular wires tethered between contacts. Molecular wires, especially biomolecules with nanometer size in nature, will be key components in nanoelectronics, as they offer much more than just charge transport and connection with the outside world. We are interested in an integrated approach that can be used to study all the parameters and thus obtain the most information.




  • Single molecular interaction & recognition of biological systems: When studying systems in which molecular individuality matters, single-molecule experiments offer several important advantages over ensemble measurements. First, single-molecule measurements provide important information that is “averaged out” in ensemble results. Second, by conducting many sequential measurements, they allow one to determine the distribution of molecular properties and investigate the inhomogeneous systems. Finally, they permit observation of rarely populated transients that are difficult or impossible to capture using bulk measurements. In this research we are to detect biological events at the single-molecule level, which will be key to scientific advances in understanding, identifying, and developing therapies that promote human health.