Background
Environmental barriers by ALD

By encapsulation, we mean the implementation of protection against the environment in which a device, object, or food product is used or stored. This protection consists of creating a barrier to the diffusion of permeants from the environment or, conversely, to their diffusion from the protected entity. Given the focus of this article, we consider here only passive barrier approaches—that is, those designed to slow the diffusion of permeants from a rich medium to a lean medium—and not active approaches in which permeants are trapped by functional molecules.

Due to the development of various ALD deposition processes, their uses for encapsulation are expanding into an increasingly wide range of applications, from food packaging to microelectronic devices. Given this variety, it is important to introduce the key elements that distinguish the different fields of application:

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