Swelling of PDMS networks in solvent vapours; applications for passive RFID wireless sensorsElectronic supplementary information (ESI) available: RFID tag design and dimensions. Plot of moles of solvent vapour absorbed into elastomer after 72 hours exposure. Volume and weight swelling ratios, Hansen solubility parameters, Ra and Ranking for each solvent. Plots of Ra versus moles and QW. Plots of QV, QW and moles versus vapour pressure. 3D plots of δtvs. vapour pressure versus QW/moles. Details o

The relative degree of swelling of a poly(dimethylsiloxane) (PDMS) network in organic vapours is demonstrated to be related to the chemical and physical properties of the organic compounds. The swelling ratio, based on volume change, Q V , is directly correlated with the Hansen solubility parameters, δ d , δ p and δ h and the vapour pressures of the organic vapours employed. A practical use for such PDMS networks in combination with an understanding of the relationship is demonstrated by the use of PDMS as a mechanical actuator in a prototype wireless RFID passive sensor. The swelling of the PDMS displaces a feed loop resulting in an increase in transmitted power, at a fixed distance. The swelling ratio of a network polydimethylsiloxane correlates with the Hansen solubility parameters, δ d , δ p and δ h and the vapour pressures of organic vapours. The use of PDMS as a mechanical actuator in a prototype wireless RFID passive sensor is demonstrated.