Developing an ultra non-fouling SU-8 and PDMS hybrid microfluidic device by poly(amidoamine) engraftment.

A new strategy to prepare an ultra non-fouling SU-8/poly(dimethylsiloxane) (PDMS) hybrid microfluidic system is presented. We report a simple method to bond both SU-8 and PDMS surfaces to prepare the hybrid microfluidic device and then simultaneously modify both SU-8 and PDMS surfaces using poly(amidoamine) (PAMAM), a highly hydrophilic dendrimer to enhance non-fouling properties of the hybrid microfluidic channel. Water contact angle, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) are used to characterize and confirm surface modifications. Finally the non-fouling performance of the resulting microfluidic system is tested using both microbeads and Escherichia coli O157:H7 bacterial cells. We demonstrate that the obtained hybrid microfluidic system shows a significant microbead adsorption suppression of 99.7%, an ultra non-fouling performance that has not been reported in the literature before; in addition, 95% bacteria surface adsorption suppression is also obtained. Considering the significantly improved non-fouling performance and the ease of preparing the hybrid microfluidic system, we anticipate that this strategy will find wide applications in biosensing and detection.