Microfabrication techniques

Microfabrication techniques used for the production of MEMS (micro electro-mechanical systems) have been successfully used to produce highly efficient micro fluidic systems. 

Innovation - advocates and opponents origin from microtechnology list of microfabrication techniques selectivity and efficiency as main driver for industrial implementation special properties and general advantages of micro reactors process-development issues BASF investigations on liquid/liquid and gas-phase reactions micro reactors as ideal measuring tools production in micro reactors as exception, the rule will be transfer to mm-sized channels [111],... 

Today s use of microtechnical products microfabrication techniques general advantages of micro flow parallelization for screening steep transport gradients plant safety numbering-up industrial response outlook on market [222]. 

Microfabrication techniques with the features of integration, reproduction and precision are particularly suitable for the implementation of miniaturized designs and significant reduction in product costs. A miniaturized magnetic resonance probe for on-line/in-line flow studies can be microfabricated by combining an rf coil [45, 46] with microfabricated gradients [47] and electronics [48] around a small tube/capillary. 

Recent developments in microsystems technology have led to the widespread application of microfabrication techniques for the production of sensor platforms. These techniques have had a major impact on the development of so-called Lab-on-a-Chip devices. The major application areas for theses devices are biomedical diagnostics, industrial process monitoring, environmental monitoring, drug discovery, and defence. In the context of biomedical diagnostic applications, for example, such devices are intended to provide quantitative chemical or biochemical information on samples such as blood, sweat and saliva while using minimal sample volume. 

It is important to note that the enhancements mentioned above are achievable using current planar microfabrication techniques and the resultant sensor chips are mass-producible, low-cost and disposable and also have the potential to be integrated into a variety of diagnostic microsystems. This work has significant implications for the production of low-cost, yet efficient measurement platforms for applications in modem society. 

Zhang, Advani, and Prasad [51,52] also used microfabrication techniques in order to develop a thin, perforated copper foil and use it as a cathode DL in a PEMLC. In addition to the metal DL, an "enhancement" layer was used that consisted of a porous material locafed befween the perforated copper foil and fhe LF plate (CLP was used in fhis study). This layer improved the overall short-term performance and wafer managemenf of fhe cell. Flowever, the authors did not discuss any possible long-term issues related to contaminahon of the membrane due to the use of a copper DL. 

Z. Y. Xiao, G. Z. Yan, C. H. Feng, P. G. H. Ghan, and I. M. Hsing. A silicon-based fuel cell micropower system using a microfabrication technique. Journal of Micromechanics and Microengineering 16 (2006) 2014 2020. 

Microreactors evolved from the process intensification concepts and microfabrication techniques developed for the microelectronics industry. Process intensification was pioneered in the 1970s, arguably by Imperial Chemical Industries (ICI) researcher Colin Ramshaw, who began developing technologies and approaches that considerably reduced the physical size of unit operations while maintaining their... 

Microfabrication techniques Optical and compact discs Ceramic surface structures Catalyses... 

In the early years of AFM operation, the cantilevers were cut from a metal foil, and the tips were made from crushed diamond particles, picked up by a piece of eyebrow hair, and painstakingly glued manually on the cantilevers. This situation has changed completely since the methods for mass production of cantilevers with integrated tips were developed. A review of various methods for making cantilevers using standard microfabrication techniques was published by Albrecht et al. (1990), and an improved method is described by Akamine et al. (1990). Those AFM cantilevers with integrated tips are now available commercially. 

Many of the devices that have thus far been envisioned as products of nanotechnology (e.g., nanoscale environmental sensors, information processors. and actuators) cannot be produced by the large-scale microfabrication techniques currently in use. The further development of nanotechnology hinges on the understanding and manipulation of physical laws and processes at the nanometer level, such as electronic, interatomic, and mter-molecular interactions that can be manipulated lu allow efficient assembly of nanostructures. 

The packaging (i.e., electrical insulation for operation in electrolytes) is more difficult with SAWs due to their rectangular geometry. SAWs are easier to fabricate with lithographic microfabrication techniques and therefore are more suitable for use in an array (Ricco et al., 1998). The choice of electrode materials is critical for QCM, where acoustic impedance mismatch can result in substantial lowering of the Q factor of the device. On the other hand, it does not play any role in the SAW devices. The energy losses to the condensed medium are higher in SAWs and this fact makes them even less suitable for operation in liquids. Nevertheless, SAW biosensors have been reported (Marx, 2003). 

The ion controlled diode was an initial attempt to isolate the active electronics from the chemical solution by producing a metallic-like via that allows the isolation of the chemically sensitive region from an area where electronic components could be deposited (41,42). However, the limited precision of the non-standard microfabrication techniques made this process difficult and costly. Since this device is still essentially a capacitive membrane-insulator-semiconductor structure like the chemfet, the same problems of hermetic isolation of the gate remain. 

Background. The term microsensor denotes a transducer that, in some fashion, exploits advanced miniaturization technology, whether an adaptation of integrated circuit technology, or some other microfabrication technique. Within the past decade, a myriad of microsensors have been developed, with capabilities for measurement of temperature, pressure, flow, position, force, acceleration, chemical reactions, and the concentrations of chemical species. The latter measurements, of chemical species, are intrinsically more difficult than the measurement of mechanical variables because in addition to requirements of accuracy, stability, and sensitivity, there is a requirement for specificity. 

In order to address the needs of decentralized (field) testing, it is necessary to move away from such cumbersome electrodes and operation. The exploitation of advanced microfabrication techniques allows the replacement of traditional ( beaker-type ) electrochemical cells with... 

Usually, microfabrication techniques are used to prepare cantilevers with integrated tips of various shapes, mass and spring constants [197,198]. Depending on the cantilever geometry and material used to construct the cantilever [52], the frequency of commercial cantilevers typically varies from 15 kHz to more than 500 kHz, and the spring constants range from 0.01 to 100 N/m. Micromachining techniques can be used to prepare special probes such as meander-type cantilevers for bidirectional force microscopy [199]. 

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