Microfabrication, advantages

Better chemistry through confinement economy of scale limits and expenditure of scale-up micro reactors origin from microfabrication expert opinions general advantages of micro flow hybrid construction industry s efforts chip micro reactors numbering-up vision of computer-like chemical workstation [205]. 

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]. 

Another approach has been to immobilize proteins within arrays of microfabricated polyacrylamide gel pads (Arenkov et al., 2000). Nanoliters of protein solutions are transferred to 100 x 100 x 20-pM gel pads and assayed with antibodies that are labeled with a fluorescent tag. Antigen imbedded in the gel pads can be detected with high sensitivity and specificity (Arenkov et al., 2000). Furthermore, enzymes such as alkaline phosphatase can be immobilized in the gel pads and enzymatic activity is readily detected upon the addition of an indicator substrate. The main advantage of the use of the threedimensional gel pad for fixation of proteins is the large capacity for immobilized molecules. In addition, the pads in the array are separated from one another by a hydrophobic surface. Thus, each pad behaves as a small test tube for assay of protein-protein interactions and enzymatic reactions (Arenkov et al., 2000). The disadvantage of the method is the need to microfabricate the array of gel pads in that microfabrication is... 

A chip-based nanospray interface between an HPLC and the MS has been introduced by Advion Biosystems (Ithaca, NY). This instrument aligns a specialized pipette tip with a microfabricated nozzle, set in an arrayed pattern on a silicon wafer. The advantage of this interface is that each sample is sprayed through a new nozzle, thus virtually eliminating cross contamination. 

The second device with which surface forces can be measured directly and relatively universally is the atomic force microscope (AFM) sometimes also called the scanning force microscope (Fig. 6.8) [143,144], In the atomic force microscope we measure the force between a sample surface and a microfabricated tip, placed at the end of an about 100 //,m long and 0.4-10 //,m thick cantilever. Alternatively, colloidal particles are fixed on the cantilever. This technique is called the colloidal probe technique . With the atomic force microscope the forces between surfaces and colloidal particles can be directly measured in a liquid [145,146], The practical advantage is that measurements are quick and simple. Even better, the interacting surfaces are substantially smaller than in the surface forces apparatus. Thus the problem of surface roughness, deformation, and contamination, is reduced. This again allows us to examine surfaces of different materials. 

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