More than just scratch'n'sniff

In addition to its best-known (and most fun) usage, microencapsulation is used in a variety of ways to enhance our lives, in somewhat more mundane ways. Fundamentally, the technology involves wrapping tiny amounts of material in a capsule or shell, which can be released under controlled circumstances. There are various mechanisms used to carry this out, and a wide variety of applications.

The mechanisms include: rupture of the caspule wall, dissolving or melting the wall, and diffusion through the wall. Each has its advantages and uses. The capsule size can also vary enormously, from a micron in diameter to several millimeters, depending on applications.

Applications include the ubiquitous scratch-and-sniff, NCR (carbonless copy) paper, slow-release medicines, "instant" baking mixes and detergents, through to medicines.

For example, many prescription drugs release their contents over a period of time, by wrapping the medication in capsules of varying thickness or material - these dissolve at different rates, allowing the dosage to be controlled over a period of time.

Many washing powders and dishwasher detergents use a similar principle, releasing some elements, such as bleach, enzymes or conditioner only when certain conditions are met - temperature and/or time. This enables the product to be more effective, and gives the user fewer tasks to carry out.

Some packaged baking mixes include encapsulated ingredients to delay chemical reactions until proper temperatures are reached, for example, raising agents may need be released later in the baking process.




http://www.swri.org/3pubs/ttoday/summer/microeng.htm.

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