Study of modification wetting properties of the surface of polydimethylsiloxane and the microchannel after exposure by high-frequency plasma in oxygen

Soft lithography is a general technique for micro patterns fabrication in polydimethylsiloxane (PDMS). The surface of PDMS should be treated by physical and/or chemical methods depending on the end goal of modification. An important factor to ensure reproducible measurements on microfluidic chips is the stability of the obtained properties of treatment surfaces in time. We have investigated the change of wetting properties of the microchannel and the open surface of PDMS after plasma treatment depending on storage time. The estimation of the contact angle in the microchannel allow to evaluate the efficiency of processing or modification of the working surface. The possibility of determining the relationship between the contact angle on the substrate of PDMS and the meniscus of the liquid in the channel is discussed.