Polydimethylsiloxane (PDMS), due to its good mechanical properties, optical properties and chemical stability, easy processing and low price, has become the preferred material for the fabrication of microfluidic chips. However, since PDMS are themselves highly hydrophobic, porous materials. In the process of sample separation, especially for biomolecules, due to adsorption, serious trailing phenomenon is likely to occur, which may eventually lead to separation failure, severely limiting the application of PDMS in the field of microfluidic chips. Therefore, it is particularly important to modify the surface of PDMS hydrophilic and inhibit its adsorption on the separation.

At present, the methods of surface modification of PDMS are mainly divided into physical and chemical methods. Physical methods include Plasma treatment and ultraviolet ozone radiation treatment. Chemical methods include surfactant treatment and graft copolymerization.

Physical methods

Physical methods mainly use physical technology to oxidize and crosslink PDMS surface groups, change the surface chemical structure, and improve hydrophilicity.

Plasma treatment

Plasma is an ionized gaseous substance composed of atoms stripped of some electrons and electrons generated by ionizing atoms. Plasma is mainly divided into high temperature plasma and low temperature plasma. Among them, low-temperature plasma can be produced in the laboratory environment, especially oxygen plasma. The hydrophobic silicon-methyl group on the PDMS surface can be converted into hydrophilic groups such as silicon-hydroxyl group through the action of plasma, which is widely used in the sealing and surface modification of PDMS microfluidic chips.

Jean-philippe Frimat et al. selectively treated PDMS surface by atmospheric plasma technology. After using treated PDMS chips to culture cells, the PDMS itself is very hydrophobic cells can not adhere to the growth, only in the plasma modified site can grow, so as to achieve highly accurate control of cell culture. This technique provides a fast, accurate and low-cost method for the production of cell templates.