Microfluidic Sensors with Impregnated Fluorophores for Simultaneous Imaging of Spatial Structure and Chemical Oxygen Gradients Jay W. Grate Bingwen Liu Ryan T. Kelly Norman C. Anheier Thomas M. Schmidt 10.1021/acssensors.8b00924.s001 https://acs.figshare.com/articles/journal_contribution/Microfluidic_Sensors_with_Impregnated_Fluorophores_for_Simultaneous_Imaging_of_Spatial_Structure_and_Chemical_Oxygen_Gradients/7605413 Interior surfaces of polystyrene microfluidic structures were impregnated with the oxygen sensing dye Pt­(II) tetra­(pentafluorophenyl)­porphyrin (PtTFPP) using a solvent-induced fluorophore impregnation (SIFI) method. Using this technique, microfluidic oxygen sensors are obtained that enable simultaneous imaging of both chemical oxygen gradients and the physical structure of the microfluidic interior. A gentle method of fluorophore impregnation using acetonitrile solutions of PtTFPP at 50 °C was developed leading to a 10-μm-deep region containing fluorophore. This region is localized at the surface to sense oxygen in the interior fluid during use. Regions of the device that do not contact the interior fluid pathways lack fluorophores and are dark in fluorescent imaging. The technique was demonstrated on straight microchannel and pore network devices, the latter having pillars of 300 μm diameter spaced center to center at 340 μm providing pore throats of 40 μm. Sensing within channels or pores and imaging across the pore network devices were performed using a Lambert LIFA-P frequency domain fluorescence lifetime imaging system on a Leica microscope platform. Calibrations of different devices prepared by the SIFI method were indistinguishable. Gradient imaging showed fluorescent regions corresponding to the fluid pore network, dark pillars, and fluorescent lifetime varying across the gradient, thus providing both physical and chemical imaging. More generally, the SIFI technique can impregnate the interior surfaces of other polystyrene containers, such as cuvettes or cell and tissue culture containers, to enable sensing of interior conditions. 2019-01-04 00:00:00 300 μ m diameter Microfluidic Sensors pore throats polystyrene containers 10-μ m-deep region 340 μ m sense oxygen chemical oxygen gradients fluid pathways lack fluorophores Leica microscope platform chemical imaging 40 μ m solvent-induced fluorophore impregnation Simultaneous Imaging microfluidic oxygen sensors Lambert LIFA-P frequency domain fluorescence lifetime imaging system Chemical Oxygen Gradients Interior surfaces SIFI method pore network devices fluid pore network Spatial Structure polystyrene microfluidic structures acetonitrile solutions tissue culture containers Impregnated Fluorophores fluorophore impregnation Gradient imaging SIFI technique