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MicroscopyInnovations


Whether a surgeon or a technician working on micromotors, all users have the same tools in their hands: a pair of tweezers, a tip, a scalpel, a needle, a pipette, or an electrode. T ese few tools cover 90% of possible manipulation tasks accomplished at light microscopes. Nanoworkbench permits complex handling tasks to be done in an SEM/FIB. T is is essentially “keyhole surgery” with four tools and an SEM/FIB in synchronous automated operation.


Scanning Ion Microscopy with Low-Energy Lithium Ions


NIST Center for Nanoscale Science and Technology


Developers: Kevin Twedt, Jabez McClelland, Brenton Knuff man, and Adam Steele


T is new microscopy method uses a magneto-optical trap ion source (MOTIS) to generate a high-brightness beam of lithium ions. A laser-cooled and trapped cloud of neutral lithium atoms is photoionized and extracted by an electric fi eld to form a highly parallel beam of ions, which is then scanned and focused by conventional scanning microscopy techniques. T e


source creates brightness in a fundamentally diff erent way from conventional sources: through reducing the transverse temperature of the ion beam to values as low as a few hundred microkelvin. T e result is a focused beam of ions with energy between 500 eV and 5 keV and a measured spot size as small as 27 nm.


Image acquisition is accomplished by collecting either secondary electrons (SEs) or backscattered ions as the beam is scanned. Because the primary ions are positively charged, insulating regions of the target charge positively and thus impede the emission of secondary electrons. For SE images the result is very strong contrast between insulating and conducting areas, with insulating regions appearing dark. Backscattered ion images, on the other hand, exhibit markedly diff erent contrast mechanisms in comparison to SE images. In particular they show a signifi cant dependence on target material atomic number. Also low-energy ion beams penetrate the surface far less than high-energy beams, making the technique more surface-sensitive. T e technique is generally applicable to over 25 atomic species, including alkalis, alkaline earths, noble gases, and several metals.


Applications of this new type of ion microscopy in secondary electron mode include imaging of diffi cult, insulating samples, such as carbon nanotube-impregnated epoxy composites and samples where a clear delineation of insulating regions is desired. In backscattered ion detection mode, contrast between phases of various compositions will benefi t. T e small surface penetration depth allows the study of samples where the topmost few nanometers are of the most interest. Looking beyond imaging, the choice of ionic species


2015 September • www.microscopy-today.com


enabled by this technology creates opportunities for implan- tation of specifi c species with nanoscale resolution. Further applications include implantation of Li + into battery materials and the extension of traditional focused ion beam capabilities such as milling, circuit editing, beam chemistry, and ion beam lithography.


3D Cell Explorer Nanolive SA


Developer: Yann Cotte, Sebastien Equis, Christian Depeursinge, Andreas Kern, and Fatih Toy


T e 3D Cell Explorer combines holography and rotational scanning to allow measurements of the refractive index distribution within the cell (3D) and over time (4D). T is holographic tomography technique off ers a means to probe living cells in their native environment without labels, stains, or interference. Rotational scanning (with


520 nm laser light) allows low-noise 3D reconstructions at a resolution below the diff raction limit of light. T e 3D Cell Explorer has a resolution of Δ xy = 200 nm and Δ z = 500 nm; it generates a 3D image (tomography) in less than a second. Traditional fl uorescence microscopy techniques rely on complicated procedures requiring time-consuming invasive specimen preparation (1–72 hours), which sometimes can be damaging to the cells. T e resulting two-dimensional images either have little contrast or are chemically stained with only a few specifi c colors. With fl uorescence techniques researchers need to decide prior to the experiment which cell parts they want to visualize, applying a maximum of two to three stains at the same time. With the 3D Cell Explorer, the refractive index distribution within the cell is measured at each pixel, and the researcher can decide aſt er the experiment which parts of the cell to visualize. T e same image data can be analyzed a limitless number of times, and various organelles can be digitally stained in contrasting colors, without interfering with the normal physiology of the cell. T e resulting dataset can be rendered in three dimensions in less than a second.


The 3D Cell Explorer offers new imaging possibilities to scientists who have a need to look at their live cells in real-time without specimen preparation or expensive staining procedures. Applications include routine medical procedures such as morphological analysis of sperm cells for in-vitro fertilization or real-time analysis of the reaction of patient cells to a specific drug. For future developments, Nanolive would like to move toward building a portable device for personalized medicine able to automatically evaluate the reaction of a person’s cells to a particular drug or cosmetic product. Other potential uses for the 3D Cell Explorer include research on cell division, cell death, cell-cell interaction, cell differentiation, intra-cellular trafficking,


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