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Advanced TEM Specimen Preparation Technology

Special Issue: Advanced TEM Specimen Preparation Technology [ 下載 PDF ]

Chien-Chun Chen

Transmission Electron Microscopy Specimen Preparation Technology: Evolution from Early Mechanical Methods to Modern Nanotechnology [ 下載 PDF ]

Tzu-Yi Yang, Yu-Lun Chueh

The transmission electron microscopy (TEM) specimen preparation is a critical technology for achieving high-resolution microscopic observations, and its development trajectory mirrors advancements in materials science and biological research. This article reviews the evolution of TEM sample preparation from early mechanical methods to modern nanotechnology, analyzing the characteristics, applications, and limitations of techniques at each stage. It also introduces the stateof-the-art cryo-electron microscopy (cryo-EM) and automated focused ion beam (FIB) systems, exploring their impact on scientific research. Through a literature review and technical comparison,this paper aims to provide researchers with a comprehensive technical reference.

Metallic Transmission Electron Microscope Specimen Preparation [ 下載 PDF ]

Wei-Yi Yang, Wei-Hsiang Hsu, Tsai Yu Hsuan, Tsai-Fu Chung

The evolution of nanotechnology has progressively shifted scientific inquiry from macroscopic observation to the atomic scale. Optical microscopy initially enabled visualization of structures beyond the resolution of the naked eye; however, its intrinsic resolution limit prompted the advent of electron microscopy. By utilizing high-energy electron beams and their interactions with matter, electron microscopy facilitates high-resolution characterization of microstructures, crystallographic orientations, chemical compositions, and atomic-scale features. Among various electron microscopy techniques, transmission electron microscopy (TEM) is particularly distinguished by its superior spatial resolution and analytical versatility. TEM has become indispensable in diverse scientific domains including materials science, semiconductors, polymers, advanced ceramics, and biomedical engineering. It enables detailed investigations of microstructural evolution, interface phenomena, defect dynamics, and precipitation mechanisms, thereby supporting the development of structure-property relationships. The fundamental operation of TEM involves the transmission of an electron beam through an ultrathin specimen (< 100 nm). The interaction between the incident electrons and the specimen generates scattering signals, which are subsequently captured by detectors to produce high-resolution images and analytical data. Given the sensitivity of TEM to sample condition, specimen preparation is of paramount importance. Critical factors such as thickness uniformity, surface integrity, contamination, and residual stress introduced during preparation can substantially affect the fidelity of imaging and interpretation. This study presents a comprehensive methodology for preparing TEM specimens from bulk metallic materials. Key steps including cutting, polishing and lapping, twin-jet electro-polishing, and low-energy ion milling (M1040 NanoMill, E.A. Fischione Instruments) are described in detail. Emphasis is placed on overcoming common technical challenges, optimizing process parameters, and ensuring reproducible specimen quality. The objective is to establish a robust protocol that enhances analytical precision and contributes to the reliability of TEM-based investigations.

Specimen Preparation for Transmission Electron Microscopy by Using Concentrated Argon Ion Beam Milling System [ 下載 PDF ]

Wei-Chih Li, Chien-Chun Chen, Tsai-Fu Chung, Yu-Ting Peng, Su-Chun Hsiao, Chien-Nan Hsiao

The most common methods for preparing transmission electron microscopy (TEM) specimens include mechanical polishing, electropolishing, and the use of a focused ion beam system. If the sample preparation method combined with an argon ion beam polishing and thinning system, it will be possible to complete the most demanding electron microscope sample preparation. An ion milling system uses argon gas as the process gas, applying electron impact to dissociate the argon gas to produce argon ion plasma, which will bombard the sample continuously to achieve the purpose of surface cleaning and thinning the sample to a thickness that allows the electron beam of a transmission electron microscope to penetrate, representing the sample in its natural state. This method has been widely used for decades. The conventional argon ion beam ion milling system on the market has an argon ion beam size of about 500 micrometers or more. With the development of science and technology, a new generation of argon ion beam polishing and thinning systems has been launched to the market, and the size of the argon ion beams is about 1-2 micrometers, allowing targeting and selected area ion milling on the area of interest. This article will discuss how the new generation of argon ion beam polishing and thinning systems can improve the quality of transmission electron microscopy specimens prepared in different methods.

Needle-shaped Specimen Preparation for Integrating 3D Electron Tomography and Atom Probe Analysis [ 下載 PDF ]

Yu-Ting Peng, Yu-Lun Liu, Su-Chun Hsiao, Chien-Nan Hsiao, Chien-Chun Chen

With the development of three-dimensional atomic-scale tomography, the requirements for specimen preparation technology have been increasing in recent years. High-quality 3D tomographic reconstruction depends on precise sample morphology. Whether it is atomic electron tomography (AET) or atom probe tomography (APT), needle-shaped specimen are considered the most suitable design. In AET, the needle-shaped specimen can ensure that the observation area is not barred in different projection angles and maintain consistency in thickness and size to improve reconstruction accuracy. APT leans on a high electric field evaporation mechanism. The needle-shaped specimen ensures that the maximum electric field is concentrated at the needle tip, and improving the accuracy of element analysis. The needle-shaped specimen’s fabrication differs from the traditional lamella fabrication method for transmission electron microscopy (TEM). This article will describe the fabrication process of needle-shaped specimen and explore the differences between the traditional lamella specimen to improve the accuracy and reliability of 3D atomic-level microscopic analysis.

Advanced Cryo-TEM Specimen Preparation Technology [ 下載 PDF ]

Shih-Hsin Huang, Wei-Hau Chang

Cryo-electron microscopy (cryo-EM) has emerged as a pivotal platform for structural biology research, This review systematically examines the developmental trajectory of cryo-transmission electron microscopy (cryo-TEM) specimen preparation techniques, spanning from Jacques Dubochet's pioneering plunge-freezing methodology to contemporary advanced preparation protocols. First, vitreous ice thickness control proves critical for imaging quality optimization. The ideal thickness range of 20-100 nm necessitates careful balance between sample embedding integrity and electron penetration efficiency. However, the air-water interface (AWI) bottleneck continues to constrain the success rates of high-resolution structural determination. Scientists have demonstrated that AWI-induced biomolecular denaturation, preferred orientation artifacts, and heterogeneous particle distribution significantly compromise single-particle analysis reconstruction quality. Addressing these fundamental challenges, we listed three principal innovative solution strategies: (1) grid material enhancements, encompassing graphene support films, affinity grids, and self-wicking grid technologies; (2) instrumentation optimization approaches, including Spotiton rapid vitrification systems, VitroJet blotting-free methodologies, and cryo-focused ion beam milling techniques; (3) sample formulation modifications utilizing surfactants, LEA proteins, and other protective additives. Finally, in material science applications, cryo-EM technology demonstrates extensive potential for investigations of battery materials, soft matter polymers, and electrocatalyst systems.

Advanced Transmission Electron Microscope Specimen Preparation Technology: Manufacturing and Development of Liquid Cell TEM Specimens [ 下載 PDF ]

Jui-Yuan Chen, Chun-Wei Huang, Wen-Wei Wu

The development and applications of liquid transmission electron microscopy (LCTEM) technology are discussed in this article. The LCTEM overcomes the limitation that traditional TEM can only observe solid samples, bringing new opportunities to the fields such as materials science, biomedicine, and other fields. This article not only introduces the development of LCTEM samples, including improvements in resolution, sealing, and ease of operation, but also introduces the one-piece LCTEM sample developed by our group. The application of LCTEM in materials science research is demonstrated through the study of ZnO nanowires and Au-Cu2O core-shell nanostructures. Finally, we discuss the challenges of LCTEM technology and envision its future directions.

The K-kit Innovative Microchip for in-situ Electron Microscopy of Nanofluids [ 下載 PDF ]

Hung-Jen Chen

With the expanding applications of nanofluids, global standards for the analysis of liquidphase nanoproducts are becoming increasingly stringent, requiring precise characterization of nanoparticle morphology and distribution in solution. In recent years, transmission electron microscopy (TEM) has made significant advancements in in-situ liquid analysis, particularly with the development of microfluidic silicon chip technology. This article introduces an innovative microfluidic chip, “K-kit,” which uses capillary forces to quickly load the solution, is compatible with various brands of TEM equipment, and enhances nanoparticle image contrast through wet negative staining. K-kit offers several unique advantages and has been widely applied in academic research as well as industries such as electronics, chemical engineering, pharmaceuticals, and food etc.