3 - Packaging and coating materials for implantable devices

Implantable micro-electromechanical systems (MEMS) offer a valuable means of sensing and actuation within the body at unprecedented levels of miniaturisation and internal functional complexity. However, function can be compromised by moisture uptake and adverse interactions within the body. Consequently, packaging materials serve as barrier phases for controlling exchange of solutes and furnishing biocompatible surfaces for MEMS devices. This chapter covers a range of coatings used to protect MEMS devices in the body. Surface modification and bioactive agent release are described as strategies for enhancing biocompatibility and reducing surface fouling. The full range of mechanical, permeability and chemical features of packaging materials are involved in the extended survival of MEMS implants and are described for contemporary packaging materials.