PDMS

PDMS stands for polydimethylsiloxane, a silicone-based polymer composed of a silicon–oxygen backbone with pendant methyl groups. It is a viscoelastic elastomer that is optically transparent, chemically inert, heat resistant, and highly permeable to gases. In typical use, PDMS is supplied as a two-part kit: a base polymer and a curing agent. The mixture is often cast into molds, degassed to remove air bubbles, and cured by heating to around 60–80 °C, though room-temperature curing is also possible for longer times.

PDMS is widely employed in microfabrication, soft lithography, and microfluidics because it can be molded with high resolution, bonds readily to itself and to glass or silicon, and allows optical access for microscopy. Its gas permeability supports cell culture and gas-driven microfluidic operations. The material is relatively inexpensive and can be fabricated rapidly, making it a common choice for prototyping microfluidic devices, microchannels, valves, and microreactors. Surface modification methods, such as plasma treatment or silanization, are used to tailor wettability and bonding characteristics.

Key properties and limitations include surface hydrophobicity, which can hinder initial wetting but can be temporarily overcome by surface treatments. PDMS can swell in contact with many organic solvents and may absorb small hydrophobic molecules, potentially affecting chemical compatibility and analyte concentrations in some applications. It can also exhibit changes in mechanical properties with aging and solvent exposure. For applications requiring solvent resistance or long-term chemical stability, alternatives or protective coatings may be used.