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MEMS (microelectromechanical systems) for ''in situ'' mechanical characterization refers to microfabricated systems (lab-on-a-chip) used to measure the mechanical properties (Young’s modulus, fracture strength) of nanoscale specimens such as nanowires, nanorods, whiskers, nanotubes and thin films. They distinguish themselves from other methods of nanomechanical testing because the sensing and actuation mechanisms are embedded and/or co-fabricated in the microsystem, providing — in the majority of cases— greater sensitivity and precision. This level of integration and miniaturization allows carrying out the mechanical characterization ''in situ'', i.e., testing while observing the evolution of the sample in high magnification instruments such as optical microscopes, scanning electron microscopes (SEM), transmission electron microscopes (TEM) and X-ray setups. Furthermore, analytical capabilities of these instruments such as spectroscopy and diffraction can be used to further characterize the sample, providing a complete picture of the evolution of the specimen as it is loaded and fails. Owing to the development of mature MEMS microfabrication technologies, the use of these microsystems for research purposes has been increasing in recent years. Most of the current developments aim to implement ''in situ'' mechanical testing coupled with other type of measurements, such as electrical or thermal, and to extend the range of samples tested to the biological domain, testing specimens such as cells and collagen fibrils. ==Mechanical characterization at the nanoscale== Typical macroscale mechanical characterization is mostly performed under uniaxial tensile conditions. Despite the existence of other methods of mechanical characterization such as three-point bending, hardness testing, etc., uniaxial tensile testing allows for the measurement of the most fundamental mechanical measurement of the specimen, namely its stress-strain curve. From this curve, important properties like the Young’s modulus, Yield strength, Fracture Strength can be computed. Other properties such as toughness and ductility can be computed as well. At the nanoscale, owing to the reduced size of the specimen and the forces and displacements to be measured, uniaxial testing or any mechanical testing for that matter, are challenging. As a result, most tests are carried in configurations other than uniaxial-tensile, using available nanoscale science tools like the atomic force microscope (AFM) to perform a three-point bending test, SEM and TEM to perform bending resonance tests and nanoindenters to perform compression tests. In recent years, it has been found that results are not completely unambiguous. This was exemplified by the fact that different researchers obtained different values of the same property for the same material. This spurred the development of MEMS with the capability of carrying out tensile tests on individual nanoscale elements. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「MEMS for in situ mechanical characterization」の詳細全文を読む スポンサード リンク
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