Device Testing Approaches

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A short appendix on test strategies, which summarizes time-saving devices for approaching specific types of questions used on most objective examinations, is also included. 

This section outlines several approaches to characterizing the elastic modulus of thin films and the interface toughness when bonded to substrates. Naturally, there is an elastic enormous variety of test configurations that can be used attention here is limited to those with specimen fabrication that is similar to that used for typical microfluidic devices. The text by Freund and Suresh [32] describes additional test approaches, particularly those pertaining to quantifying the effects of mode-mixity on interface toughness. 

In the present work, we summarize recent observations on the coalescence behavior of several oil-water-surfactant systems. We are particularly interested in the behavior exhibited by low tension systems and the role of bulk phase viscous effects and dynamic interfacial properties such as interfacial shear and dilatational viscosities. Also, a new experimental approach for conducting coalescence studies is described which involves tests in an inclined spinning drop device. This approach allows for coalescence tests under controlled conditions and provides an efficient method for quickly screening and evaluating different surfactant systems. 

Manufacturing defects are the result of the havoc inherent in manufacturing processes. These defects result in faults that may be very easy to detect and to correlate with their root cause(s), but thk k a function of the test approach. Some manufacturing defects can still be difficult to detect and resolve, as the example given of a solder open on a device input pin shows (Fig. 55.2). 

Laser ablation systems hold considerable promise if restenosis (reblocking of the arteries) rates are reduced. The rate as of 1995 is 30%, typically within six months. Mechanical or atherectomy devices to cut, shave, or pulverize plaque have been tested extensively in coronary arteries. Some of these have also been approved for peripheral use. The future of angioplasty, beyond the tremendous success of conventional balloon catheters, depends on approaches that can reduce restenosis rates. For example, if appHcation of a dmg to the lesion site turns out to be the solution to restenosis, balloon catheters would be used for both dilating the vessel and deUvering the dmg. An understanding of what happens to the arterial walls, at the cellular level, when these walls are subjected to the various types of angioplasty may need to come first. 

Our screening and testing of multicomponent capsules/beads is incomplete. However, it offers a novel approach for the material selection for immobilization devices, which permits the simultaneous control of permeability, mechanical stability, and compatibility. The alternative multicomponent systems presented herein offer new possibilities for biomaterials, particularly those employed in bio artificial organs. 

FDA device regulation is focused on the device and the device manufacturer. CLIA, on the other hand, focuses on laboratory quality, including the quality of the laboratory test results provided by the devices used, whether developed in-house or as a test kit in commercial distribution to multiple laboratories. The programs differ substantially in approaches and in data requirements. FDA requires unique submissions for each test under its purview, evaluates both performance and labeling, and requires demonstration of analytical validity and clinical validity as appropriate. CLIA inspects laboratories using a system approach based on key probes of the operating system. CLIA requires a demonstration of analytical performance and quality control but does not require a showing of either clinical validity or clinical utility. 

Natural weathering (see Section 5.2.5) can be accelerated directly by exposure in a climate more severe than that expected in service. There are established test sites for this purpose in Australia and in the hotter states of the USA. The severity of exposure can also be maximised by arranging for the plane of the test pieces to automatically follow the sun. Another approach is to use a Fresnel mirror concentrating device that increases the intensity of sunlight falling on the test piece. These procedures are standardised in ISO 877 [25]. 

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