Reversible bonding by dimethyl-methylphenylmethoxy siloxane – based stamping technique for reusable poly(dimethylsiloxane) microfluidic chip

Reversible packaging is very desirable for microfluidic chips: it allows changing the chip upper cap when it is damaged, cleaning and reusing the chip bottom substrate. This latter case becomes even more attractive when integrated components are present on the substrate and have required a complex and expensive microfabrication process. The feasibility of poly(dimethylsiloxane) (PDMS)/PDMS and PDMS/glass reversible bonding is demonstrated using the stamping technique. Dimethyl-methylphenylmethoxy siloxane (DMPMS), a type of silicone conformal coating, is used as an adhesive layer between the PDMS channel and the substrate (PDMS or glass). This technique is easy to perform as it only needs spin-coating and thermal curing steps. The bond strength is suitable for high working flow rate/pressure of liquid in the channel (up to 500 μl/min and 200 kPa). The cycle `pealing/bonding´ of the cap can be repeated up to five times. In addition, an MTT cell proliferation assay has been performed and suggests the non-cytotoxicity of DMPMS. Thus, the DMPMS-stamping bonding technique opens new perspectives for PDMS biochips where plasma treatment is not possible such as functionalised surfaces.