This study is focused on the application of a dual surface coating on poly(dimethylsiloxane) (PDMS) flow chambers, which aims to inhibit the contact activation pathway of coagulation. Polyethylene glycol (PEG) is a commonly used biocompatible molecule due to its hydrophilic nature and capacity to reduce protein adsorption. Corn trypsin inhibitor (CTI) is a selective inhibitor of Factor XII, which is the initial factor responsible for activating the intrinsic pathway of coagulation. By sequentially applying these two coatings to PDMS substrates, we expect the PEG-CTI coating to decrease blood clot formation and reduce fibrinogen deposition on surfaces compared to uncoated surfaces. Our results indicate that the PEG-CTI coating was successful in significantly reducing both cell adsorption and fibrinogen deposition to the surfaces of PDMS flow chambers. This study is a step toward applying PEG-CTI surface coatings to PDMS microfluidic artificial lungs, in which the surface interaction between the PDMS lungs and blood is a critical issue that must be mitigated to realize the full potential of this exciting therapeutic tool.