Study of the nanoscopic deformation of an annealed nafion film by using atomic force microscopy and a patterned substrate

A new approach for repeated tip-sample relocation for AFM imaging of nano and micro sized particles and cells in liquid environment

The ability to repeatedly find exact the same nano region-of-interest (nROI) is essential for atomic force microscopy (AFM) studies of heterogeneous environmental samples. The large variety of methods makes it difficult to find the most suitable one for a specific research question. We thus conducted a literature research for nROI relocation methods and organized the found references in order to give an overview over relocation methods including the advantages, limitations and documented applications. This survey of nROI relocation methods and their key information facilitates the selection of appropriate methods with respect to a specific research question. Based on this survey, we developed a new AFM relocation approach urgently needed for the study of nano and micro sized particles and cells in air and aqueous environment. This approach uses commercially available TEM grids fully embedded in a semitransparent resin as a glue body on top of which particles and cells are fixed. Relocation of nROI within one grid is based on easily recognizable sample features in micro and nanometer scale. The stable sticking of the studied mineral particles and bacterial cells allows repeated measurements of the same nROI with differently functionalized tips in air as well as in water. Our simple, fast, and cost-effective method allows relocation with an accuracy of 10-40 nm and enables the implementation of AFM/ESEM correlative microscopy.

New Insights into Perfluorinated Sulfonic-Acid Ionomers

In this comprehensive review, recent progress and developments on perfluorinated sulfonic-acid (PFSA) membranes have been summarized on many key topics. Although quite well investigated for decades, PFSA ionomers' complex behavior, along with their key role in many emerging technologies, have presented significant scientific challenges but also helped create a unique cross-disciplinary research field to overcome such challenges. Research and progress on PFSAs, especially when considered with their applications, are at the forefront of bridging electrochemistry and polymer (physics), which have also opened up development of state-of-the-art in situ characterization techniques as well as multiphysics computation models. Topics reviewed stem from correlating the various physical (e.g., mechanical) and transport properties with morphology and structure across time and length scales. In addition, topics of recent interest such as structure/transport correlations and modeling, composite PFSA membranes, degradation phenomena, and PFSA thin films are presented. Throughout, the impact of PFSA chemistry and side-chain is also discussed to present a broader perspective.

A rapid and automated relocation method of an AFM probe for high-resolution imaging

The atomic force microscope (AFM) is one of the most powerful tools for high-resolution imaging and high-precision positioning for nanomanipulation. The selection of the scanning area of the AFM depends on the use of the optical microscope. However, the resolution of an optical microscope is generally no larger than 200 nm owing to wavelength limitations of visible light. Taking into consideration the two determinants of relocation-relative angular rotation and positional offset between the AFM probe and nano target-it is therefore extremely challenging to precisely relocate the AFM probe to the initial scan/manipulation area for the same nano target after the AFM probe has been replaced, or after the sample has been moved. In this paper, we investigate a rapid automated relocation method for the nano target of an AFM using a coordinate transformation. The relocation process is both simple and rapid; moreover, multiple nano targets can be relocated by only identifying a pair of reference points. It possesses a centimeter-scale location range and nano-scale precision. The main advantages of this method are that it overcomes the limitations associated with the resolution of optical microscopes, and that it is label-free on the target areas, which means that it does not require the use of special artificial markers on the target sample areas. Relocation experiments using nanospheres, DNA, SWCNTs, and nano patterns amply demonstrate the practicality and efficiency of the proposed method, which provides technical support for mass nanomanipulation and detection based on AFM for multiple nano targets that are widely distributed in a large area.

In-situ observation and relocation method of nanomaterial samples based on microscope systems

Taking poly(lactic acid) microbubbles and purple membranes as examples, a general in situ observation and relocation method of nanomaterial samples based on microscope systems was reported. First, a four-grade coordinate with different precisions was marked around a substrate by UV lithography. Second, using optical microscope and scanning probe microscope, special positions of poly(lactic acid) microbubbles and purple membranes were observed, respectively. Third, the four-grade coordinate value corresponded to the special sample position, and the distance between the special position and coordinate edge were recorded, respectively. Finally, the special position can be easily found again, or the sample in the special position can be manipulated and secondary processed based on the recorded coordinate value and distance, after the sample was removed and then was reset on the sample stage of microscope. The in situ observation and relocation method can be applied in different microscope systems and different sample substrates, and will have potential applications in the manipulation and the secondary process of micro- and nano-devices.