Hemocompatibility of EpoCore/EpoClad photoresists on COC substrate for optofluidic integrated Bragg sensors

We report on the hemocompatibility properties of EpoCore/EpoClad UV-structurable epoxy resins in combination with a TOPAS(R) cyclic olefin copolymer substrate for potential application as an optofluidic biosensor chip. For comprehensive hemocompatibility tests human blood is directly exposed to layers of the different chip materials up to 3 h. Counts in white blood cells, red blood cells and platelets as well as hemolysis and concentration of thrombin/antithrombin complex (TAT), of complement fragment (C5a) and heparin are determined. Our results attest TOPAS and the epoxy resins high hemocompatibility properties. Subsequently, an optofluidic chip fabrication concept with integrated Bragg grating sensors is suggested. Bragg gratings are directly inscribed into rectangular EpoCore waveguides on TOPAS 6017 substrate by coherent phase mask illumination. UV-structured EpoClad resist serves both as waveguide cladding and microfluidic channel network. In evanescent field refractive index sensing experiments sensitivities up to 76.9 nm/RIU and a maximum refractive index resolution of 1.3.10-5 are achieved by detecting multimode Bragg reflections. (C) 2016 Elsevier B.V. All rights reserved.