Materials

Microfabrication techniques and physical–chemical properties of the materials play a key role in microfluidic applications. Organic polymers, glasses, silicon, metals, ceramics, paper, and so on are all examples of materials involved in microfluidic applications. Even if these materials have quite different physical and chemical properties, they must be biocompatible, especially in cellular microfluidic applications. A material totally inert toward the biological environment does not exist, and even a small variation in the macromolecular architecture can generate relevant differences in terms of cytotoxicity, thrombogenicity, interaction with cells and tissues, biostability, and even more. Specific treatments can be performed to modify the material biocompatibility, especially at the surface, where the interaction with cells occurs. Surface parameters like charge, roughness, stiffness, and wettability play a key role in cellular response and will be discussed in detail in the next sections. Materials properties should also be evaluated when image-based cellular screenings come into account. Hence optical properties become relevant in the decision of the material. In this chapter the mechanical, physical, and chemical properties of the materials most used in microfluidics will be discussed, with the aim of helping the reader in a preliminary choice of the desired material, suitable for a specific microfluidic application.