Imaging soft biological samples in liquid with Atomic Force Microscope has long stood as a very challenging task. Until recently, most of the works in this field has been carried out in tapping mode AFM, during which the cantilever driven by a piezoelectric actuator vibrates in the vicinity of the cantilever's resonance frequency, and briefly touches the sample surface at the bottom of each vibration cycle, resulting in a decrease of its oscillation amplitude. By keeping such amplitude at a preset value using feedback control, a topographic image of the sample surface is obtained. However, stable, high-resolution imaging of very fragile and sensitive biological samples such as live cells or individual proteins is not trivial in tapping mode due to potential sample distortion or even damage during the brief contact between the AFM tip and sample surface at the end of each oscillation cycle. The XE-series AFM with Crosstalk Elimination and high force Z-scanner has successfully solved these problems.
Solar cells, or photovoltaic cells, are used to convert sunlight into electrical power. As traditional power sources grow scarce, other forms of producing electrical power are gaining firm footing in the power supply mix. Solar cells are already widely used in a variety of applications - from spacecraft, to small portable devices, to farm installations, to roadway signs. As energy prices increase, public demand for solar power has surged. In order to meet the longevity, yield, and price requirements of consumers and industry, public and private sector research has increased dramatically. While traditional tools are helpful to investigate and improve solar cells, AFM/SPM offers metrology, topography and roughness analysis at much higher resolution than with optical techniques.
After two decades of evolution, Atomic Force Microscopy (AFM) has established its strong existence in the material science research field with its nanoscale resolution. Of the systems out in the market, the innovative XE-AFMs have overcome the non-linearity and non-orthogonality problems associated with traditional piezoelectric tube based AFMs. Active in both research and industrial applications including hard-disk, microchip fabrication, and quality control, the XE series has been widely adopted in the nanometrology field. The most recent addition to the XE family, the XE-Bio, has integrated the high resolution of AFM imaging and non-invasiveness capabilities Scanning Ion Conductance Microscopy with the versatility of advanced optical microscopy techniques such as scanning confocal microscopy, FRET and TIRF. Therefore, the XE-Bio is able to correlate the highest possible spatial resolution with dynamic functionality studies on live biological samples.
Since its invention in 1986 by Binnig, Quate, and Gerber, the atomic force microscope (AFM) has become an indispensable tool for investigators in the physical, materials, and biological sciences. The AFM quickly gained acceptance in these fields due to its ability to capture topographical maps of surfaces in either air or liquid with sub-angstrom and nanometer resolution. This Application Note briefly describes the basics of both optical and atomic force microscopy, followed by a discussion of some of the technical challenges of integrating these two distinct imaging modalities. In certain cases, the benefits and disadvantages of different approaches to design and integration are discussed. Lastly, a few examples of successful application of these combined imaging modalities are presented.
Many of today's high-tech products rely on nano-level functional structures, and in products such as mobile phones, integrated circuits and glasses they have already become commonplace. But with increasing demands on products and their quality, tiny structures and the ability to evaluate them are also becoming decisive factors for the production of everyday products. The experience of a ball-point pen maker shows how atomic force microscopy enables highly accurate quality control during manufacturing, eliminating entire production steps in the process. Everyone has had to contend with scratchy or messy ball-point pens, but not everyone knows that often this malfunction is the result of a manufacturing error: smooth writing depends largely on the roughness of the sphere at the tip of the pen. Its roughness needs to lie in a well-defined interval: too rough, and the pen leaks; too smooth, and it scratches and fails to transport enough ink. The roughness of this little sphere thus becomes the decisive quality indicator of the entire writing apparatus.
Over the past decade, Atomic Force/Scanning Probe Microscopy (AFM/SPM) has emerged as the leading tool for investigations at the nanoscale - doing everything from imaging, to compositional differentiation, to explorations of molecular forces. But aside from some interesting tweaks, add-ons and repackaging, the field has seen no fundamentally new instruments for several years. For the extremely high-resolution AFM/SPMs, there has literally been no completely new microscope for well over a decade. Enter the new Cypher AFM. Cypher was designed from the ground up with a host of new features and unmatched performance enabled by its revolutionary new design.
In today's addition to our Application Note series we are looking at the future of electronics and the implications for research instrumentation. We are showing two examples of atomic force microscope (AFM) applications employed in this research. Current CMOS (complementary metal-oxide-semiconductor) technology used for making integrated circuits is constantly being scaled down. These devices will reach their ultimate physical limits in 10 to 15 years. As chip structures - which currently already have reached nanoscale dimensions - continue to shrink below the 20 nanometer mark, ever more complex challenges arise and scaling appears not to be economically feasible any more. And below 10 nm, the fundamental physical limits of CMOS technology will be reached. Researchers are therefore exploring novel concepts for future nanoelectronic devices.
Today, in our Application Note series, we are covering Scanning Thermal Microscopy (SThM) - an atomic force microscopy (AFM) imaging mode that maps changes in thermal conductivity across a sample's surface. Similar to other modes that measure material properties, SThM data is acquired simultaneously with topographic data. The SThM mode is made possible by replacing the standard contact mode cantilever with a nanofabricated thermal probe with a resistive element near the apex of the probe tip. This resistor is incorporated into one leg of a Wheatstone bridge circuit, which allows the system to monitor resistance. This resistance correlates with temperature at the end of the probe, and the Wheatstone bridge may be configured to either monitor the temperature of a sample or to qualitatively map the thermal conductivity of the sample.