Batch techniques specific examples

General and site recipes are non-equipment dependent and describe the technique of the process, or how to do it in principle, they may however, specify when known, data that may be required for the equipment, for example, pressure requirements. The general recipe is defined at the level of the enterprise, whilst the site recipe is specific to a particular site. Master and control recipes describe the task, i.e. how to do it with actual resources. The master recipe is the required recipe as without it no control recipe can be created and therefore no batches can be produced. 

Materials from reputable companies may be supplied with detailed specifications and their methods of determination may be obtained, if requested. The information on specifications such as purity or content is very often available. Nevertheless, it is prudent to confirm such information. The information provided by different suppliers may vary. The type of tests carried out or the techniques used for the characterization of a particular physical property, for example, the particle size distribution, may be different. Comparison of materials from different suppliers can therefore be difficult. Sometimes, the analytical result supplied by the manufacturer is given as falling within a certain range and this gives virtually no information about batch to batch variation of the material. 

The surface acoustic wave device (SAW) is an example of a transducer that is batch fabricated using IC technology and provides improved performance. SAW devices operate at much higher frequencies than the quartz crystal oscillator (or microbalance, QCM), and this results in improved detection limitsl, 29, 30 This can make measurements of absorption into films coating the SAW device possible, under circumstances where the QCM is insufficiently sensitive. On the other hand the ( M can be used in aqueous systems, while the SAW device is essentially restricted to gas phase measurements. Here too, IC techniques have provided means to fabricate thin membranes that can be made to oscillate at frequencies similar to the SAW device, but in a mode that is not over-damped in aqueous solutions. Nevertheless, regardless of the specific oscillator involved, it is the coating films and interfaces that provide the chemical specificity required of the sensor. 

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