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Industrial Applications
Published in Vlado Valković, Low Energy Particle Accelerator-Based Technologies and Their Applications, 2022
Conventional focused ion beam systems employ a liquid-metal ion source (LMIS) to generate high-brightness beams such as Ga+ beams. Recently there has been an increased need for focused ion beams in areas like biological studies, advanced magnetic-film manufacturing and secondary-ion mass spectroscopy (SIMS). Ji et al. (2005) reviewed the status of development on focused ion beam systems with ion species such as O2+, P+and B+. Compact columns for forming focused ion beams from low energy (~3 keV), to intermediate energy (~35 keV) were discussed. By using focused ion beams, a SOl MOSFET was fabricated entirely without any masks (Fig. 4.14).
Identifying Nanotoxicity at the Cellular Level Using Electron Microscopy
Published in Suresh C. Pillai, Yvonne Lang, Toxicity of Nanomaterials, 2019
Kerry Thompson, Alanna Stanley, Emma McDermott, Alexander Black, Peter Dockery
SEM enables identification of samples down to length scales of roughly 10 nm, and images created in the SEM reveal information on the external structural arrangement, spatial distribution, and surface topography, along with the geometrical features of a structure. Micrographs display information about the exterior shape, size, orientation, and density of the sample under study. Deviations in the conventional SEM workflow are progressing with the expansion in development of the focused ion beam (FIB) and serial block face (SBF) microscopy techniques (Smith and Starborg, 2018). These processes lack the possible resolution that can be achieved with TEM but are much more time efficient and are capable of gathering much larger datasets. Another variation to the conventional use of SEM is the use of so called ‘wet imaging’ under high-vacuum conditions. This type of technique removes the need for the extensive sample dehydration and allows viewing of cell or tissue isolates in their fully hydrated state. Samples are contained on a membrane within a stable capsule adapted for SEM imaging.
Design and Manufacturing of CNT-Based Nanodevices for Optical Sensing Applications
Published in Iniewski Krzysztof, Integrated Microsystems, 2017
Ning Xi, King Wai Chiu Lai, Jiangbo Zhang, Carmen Kar Man Fung, Hongzhi Chen, T. J. Tarn
Another controllable assembly process for fabricating CNT devices is to mechanically manipulate CNTs to bridge the microelectrodes. Atomic force microscope (AFM), or scanning force microscope, was invented in 1986 by Binnig et al. [47]. Figure 18.1 shows the schematic diagram of a head scanning AFM system. Like all other scanning probe microscopes, the AFM utilizes a sharp probe moving over the surface of a sample in a raster scan. In the case of the AFM, the probe is a tip at the end of a cantilever which bends in response to the force between the tip and the sample. The surface topography is acquired by recording the bending of the cantilever at each sampling point. A single CNT attached at the tip end of an AFM cantilever were manipulated using focused ion beam [48]. But the nanotube has to be metal coated for manipulation. Hence this technology is not good for building nanoelectronic devices. A 3D manipulation of CNTs has been studied in [49], but the manipulation has to be performed under scanning electron microscopy, which limited the applications. A more general way is to manipulate CNTs using the AFM tip such that CNTs can be positioned on the substrate surface in a bare environment [50–52], but all these works limited to manipulating CNTs and none of them built nanoelectronic devices through manipulating CNTs. In short, no single process can manufacture CNT-based nanodevices nowadays. In order to overcome the difficulties to fabricate nanodevices, we have developed a hybrid manufacturing process for building CNT-based nanodevices using a DEP deposition system and AFM manipulation, the DEP deposition system can approximately deposit CNTs to metal electrodes, followed by fine manipulation by an AFM nanorobotic system. As a result, CNT-based nanodevices can be made effectively.
Bridging the gap between fundamental research and product development of long acting injectable PLGA microspheres
Published in Expert Opinion on Drug Delivery, 2022
Xun Li, Zhanpeng Zhang, Alan Harris, Lin Yang
Compared to conventional scanning electron microscopy (SEM) imaging, FIB-SEM 3D imaging experiment adds a ‘milling’ tool in the form of a focused ion beam (FIB). Due to its heavy ionic mass, the Gallium FIB removes a small amount of material, thus exposing the surface and microstructures underneath. Repetitive FIB milling followed by SEM imaging produces a stack of images which can be reconstructed into a 3D volume. Therefore, by FIB-SEM, the internal structure of PLGA microspheres could be observed and characterized as Figure 5d shows. Then, the correlation between drug distribution, porosity, and internal microstructure of PLGA microspheres could be established. And more importantly, during the in vitro release period, the drug dissolution and distribution, surface morphology, internal structure changes and even interaction between polymer and drug could be monitored and reflected by FIB-SEM [123,124]. DigiM is imaged-based platform which could provide FIB-SEM g services go beyond just the images, with AI analysis to quantify the internal microstructures. Combined with artificial-intelligence Image analytics, it might become a game changer in the area of micro/nano size area.
Molecular tissue profiling by MALDI imaging: recent progress and applications in cancer research
Published in Critical Reviews in Clinical Laboratory Sciences, 2021
Pey Yee Lee, Yeelon Yeoh, Nursyazwani Omar, Yuh-Fen Pung, Lay Cheng Lim, Teck Yew Low
More recently, advances in omics technologies have enabled the large-scale molecular profiling of tumors to detect cancer-associated molecular changes [6–8]. One such emerging tool is mass spectrometry (MS) imaging, whereby MS is used to visualize the spatial distribution of molecules such as glycan, lipids, proteins, or small-molecule drugs by their molecular masses. MS imaging can be coupled to many ionization techniques such as matrix-assisted laser desorption/ionization (MALDI), secondary ion mass spectrometry (SIMS), desorption electrospray ionization (DESI), laser ablation electrospray ionization (LAESI), and liquid extraction surface analysis (LESA). Each of these techniques differs in terms of the types of target analytes, spatial resolution, and speed of analysis. SIMS is a destructive technique that analyzes samples by directing a focused ion beam, resulting in a high fragmentation yield. SIMS has high speed of analysis and very high spatial resolution (<1 μm) and is more suitable for the analysis of metabolites and small molecule drugs [9]. DESI utilizes a combination of electrospray and desorption ionization and is applicable to a wide range of organic and biological compounds in different forms (solid, liquid, and gaseous) without requiring extensive sample preparation [10]. For more details on these ionization techniques, the readers are referred to other excellent reviews [9–11].
Diagnostic Electron Microscopy of Retina
Published in Seminars in Ophthalmology, 2018
Rishikesh Kumar Gupta, Inderjeet Kaur, Tapas C. Nag, Jay Chhablani
To create a coherent beam of electrons, the magnetic lenses (made up of the coil and soft iron) are placed-in along the path of the accelerated electrons. When the current passes through these coils, it creates an electromagnetic field. The strength of the electromagnetic field and power of magnetic lenses regulates the coherence property of the electron beams by altering the current flowing through the coil.28 A very high vacuum (approximately ranging from 10–5 to 10–8 Pascal) is maintained around the electron source and specimen, to reduce the probability of striking of the electrons to the gaseous molecule is up to almost zero while traversing through the column. Finally, this focused ion beam of electrons interacts with the specimen in a very high vacuum chamber.