Microscale machines

Burr (sharp extended material over a machined edge) formation is another critical factor in microscale machining since it affects the capability to meet desirable tolerance and geometry definition and assembly of parts. In micromachining, entrance, exit, and top (burrs occurring along the side wall of a slot or tool... 

Willner I Basnar B Willner B, From molecular machines to microscale motility of objects Application as smart materials , sensors, and nanodevices, Adv. Funct. Mater., 2007, 17, 702-717. 

Another problem of the microscale is the surface quality of the single parts of a device. Burr formation generated by mechanical micromachining or laser machining... 

Three-dimensional machining (or 3D photopolymerization or stereolithography) gives the possibility to make objects, even with complex forms, for prototyping applications. A laser beam is used for the excitation. Creating 3D microscale structures for microelectromechanical, microoptics and microfluidic applications requires to use high peak power laser pulses allowing a multiphoton (typically two photon) of the photoinitiator at the focal point. 

Microfluidic device can be used to sort cells. Fluorescence-activated cell sorter (FACS) machines have been scaled down to chip size. Single cell manipulation at a high speed is made possible by the fast response time of an integrated piezoelectric (PZT) actuator. Cells are sorted on the detected optically expression [46]. Cells can also be separated in an electric held on the basis of electrically distinguishable phenotypes [47]. Other cell sorters look at the fitness of the cell. For example, semen can be fractionated by their ability to swim through interfaces between adjacent laminar streams into separate streamlines, which enables isolation of motile, morphologically normal spermatozoa from semen samples [48]. This resulted in a microscale sperm sorter in which high-quality sperm can be isolated and used for in vitro fertilization [49]. 

In our postulation, how to automate machines in terms of operations will soon be a routine problem because of the technological maturity of actuators, sensors, and controllers. The application of automation technology will then focus on the issues of intelligence, integration, and autonomy. Another emerging trend involves the incorporation of micro-electromechanical systems (MEMSs) as sensors and controllers of automation and the microscale. However, education and training of workers who interact with intelligent and autonomous machines may be another important research issue in the future. 

At the microscale the performance of surfaces is even more critical, and hence in most cases, it is important to machine components to achieve a very good surface finish. For example, the surface roughness obtained machining HI 3 tool steel using solid carbide tools, 500 pm in diameter, is shown in Fig. 2. 

Applications for Micromachining Micromachining can be a key technology for machining of micro components, micro features, or components that lie between the macroscale and microscale domain (mesoscale components). Some typical applications for micromachining are listed below ... 

R. Eelkema, M.M. Pollard, J. Vicario, N. Katsonis, B.S. Ramon, C.W.M. Bastiaansen, D.J. Broer, B.L. Feringa, Molecular machines nanomotor rotates microscale objects. Nature 440, 163 (2006)... 

This is a fabrication procedure used to machine or modify materials on the microscale. A focused beam of high-energy ions is targeted at a material, and the impacting ions sputter atoms from the surface a prescribed scanning of the ion beam thus has the effect of a milling procedure. 

Cardiovascular disease, namely, coronary artery disease, remains the leading cause of death in the developed nations. Over the last few years, MEMS sensors have advanced the understanding of blood flow, namely, fluid shear stress, in arterial circulation. Fluid shear stress is defined as the frictional force acting tangentially on the surface of a blood vessel wall. Furthermore, the measurement of wall shear stress is important to study the durability of prosthetic valves and to monitor thrombosis or blood clots in cardiopulmonary bypass machines, artificial hearts, and left ventricular assist devices. Luminal shear stress measurement predicts the development of atherosclerotic plaque in patients at risk for acute heart attacks. In this context, the application of microscale hot-wire anemometry bridges fluid mechanics of blood flow with vascular biology. 

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