The mechanical properties of the rubber elastic polymer polydimethylsiloxane for sensor applications

Polydimethylsiloxane (PDMS) is a commercially available physically and chemically stable silicone rubber. It has a unique flexibility with a shear elastic modulus G ≈ 250 kPa due to one of the lowest glass transition temperatures of any polymer (Tg ≈ −125 ◦C). Further properties of PDMS are a low change in the shear elastic modulus versus temperature (1.1 kPa ◦C−1), virtually no change in G versus frequency and a high compressibility. Because of its clean room processability, its low curing temperature, its high flexibility, the possibility to change its functional groups and the very low drift of its properties with time and temperature, PDMS is very well suited for micromachined mechanical and chemical sensors, such as accelerometers (as the spring material) and ISFETs (as the ion selective membrane). It can also be used as an adhesive in wafer bonding, as a cover material in tactile sensors and as the mechanical decoupling zone in sensor packagings.