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Photopatternable Polymeric Membranes For Optical Oxygen Sensors, Raghu Ambekar, Jongwon Park, David Henthorn, Chang-Soo Kim
Photopatternable Polymeric Membranes For Optical Oxygen Sensors, Raghu Ambekar, Jongwon Park, David Henthorn, Chang-Soo Kim
Chemical and Biochemical Engineering Faculty Research & Creative Works
A new class of optical oxygen sensor that can be photopatternable by traditional UV lithography is presented. They are fabricated using photopatternable spin-on silicone (polydimethylsiloxane, PDMS) with oxygen sensitive luminescent dyes. It has a good adhesion property and can be applied on glass or on photopolymer (SU-8) without any additional surface treatments. The optimum mixture composition for patternable oxygen sensitive membranes is investigated and its optical properties are characterized. Proof-of-concepts for two applications, intensity-based oxygen sensing with SU-8 based structure and self-calibration fluidic oxygen sensor, are described. These photopatternable optical membranes will find many applications wherever small patterns of oxygen …
Surface Modification Of Su-8 By Photografting Of Functional Polymers For Lab-On-A-Chip Applications, Zhan Gao, David Henthorn, Chang-Soo Kim
Surface Modification Of Su-8 By Photografting Of Functional Polymers For Lab-On-A-Chip Applications, Zhan Gao, David Henthorn, Chang-Soo Kim
Chemical and Biochemical Engineering Faculty Research & Creative Works
Due to the high flexibility and versatility in the process development of microfluidic devices, an epoxybased, high-aspect ratio photoresist SU-8 is now attracting attention as the main structuring material of the fluidic channels. Manipulation of the surface properties of SU-8 channel wall is critical to attach functional films such as enzyme-immobilized layers or biocompatible layers. We describe a new in situ patterning method to form a hydrogel film on SU-8 by a photografted polymerization procedure. The hydrophobic surface of SU-8 is modified using a surface bound initiator HCPK (1-hydroxycyclohexyl phenyl ketone). A p-HEMA (poly-2-hydroxyethylmethacrylate) hydrogel film is grafted by photopolymerization …
The Anodic Dissolution Of Tungsten, James W. Johnson, Cheng-Hsiao Wu
The Anodic Dissolution Of Tungsten, James W. Johnson, Cheng-Hsiao Wu
Chemical and Biochemical Engineering Faculty Research & Creative Works
The anodic dissolution of tungsten was studied in H2SO4-K2SO4 solutions (pH = -2 to 2.5) and K2SO4-K2CO3-KOH solutions (pH = 11.5 to 14.5) at 25 C. Faradaic efficiency studies in basic solutions showed the metal to be oxidized to the +6 state. In acid solutions, a thick protective film of yellow WO3 was formed. Polarization curves possessed linear Tafel regions (slope ~ 2.3 RT/F) at potentials slightly more positive than the rest potentials. An anodic dissolution mechanism is proposed which involves a surface film …