JPK reports on how researchers at the Free University of Berlin are using the NanoWizard® ULTRA Speed AFM to study carbon-based nanoparticles (from graphene sheets).

Mr Christian Halbig of the Eigler Group at FU-Berlin with the JPK NanoWizard® ULTRA Speed AFM.

JPK Instruments, a world-leading manufacturer of nanoanalytic instrumentation for research in life sciences and soft matter, reports on the research of the Eigler Group in the Institute for Chemistry & Biochemistry at the Free University of Berlin. They are studying carbon-based nanoparticles with JPK’s NanoWizard® ULTRA Speed AFM system as part of a development of new bio-electrical devices.

PhD student, Christian Halbig, is a member of the research group led by Professor Dr Siegfried Eigler at the Institute of Chemistry & Biochemistry at the Free University of Berlin (FUB). The group is focused on the preparation and characterization of carbon-based nanoparticles. They mainly use single layered graphene sheets obtained from graphene oxide which are then modified by different functionalization techniques. These synthesized nanoparticles are then further tested for biological and technical applications in, for example, electrical devices.

AFM is one of the main tools used to have a closer look on the nanoparticles. Images obtained from AFM provide detailed information about the particle size distribution from the micron scale down to nanometer sized particles as well as particle thickness before and after functionalization. AFM is used in conjunction with 2D Raman spectroscopy and light microscopy to study graphene coated onto SiO2/Si wafers.

Asked about the benefits of using the JPK NanoWizard® ULTRA Speed AFM system, Mr Halbig says, “The biggest benefit of our new JPK AFM is its programmability. It allows us to break the limits of the scanner by the automatic generation of individual small AFM images. These can be merged then to get large area images of coated surfaces.”

The JPK AFM is a tip-scanning system controlled by a powerful software. The cantilever is mounted onto a glass cantilever holder with an optical access from the top. With this setup, it is possible to measure in liquids (water) as well as in air without changing the configuration. In addition to standard imaging modes such as contact and AC, JPK’s proprietary Quantitative Imaging (QI™) mode is available. QI™ mode works by making point-to-point force-distance curves making the analysis of, for example, mechanical properties possible. The automated setup allows the use of scripts to plan experiments and make statistical analysis from different sample areas. The system used at the Free University of Berlin also includes the more specialized electrical modes such as Kelvin Probe and Conductive AFM for the determination of the work function or electrical inhomogeneities of samples.

Right: An image of a Langmuir-Blodgett film of graphene imaged using the JPK NanoWizard® ULTRA Speed AFM.