3D printed O2 indicators

Abstract

A polymer filament, containing an O₂-sensitive lumophore pigment, platinum(II) (pentafluorophenyl) porphyrin coated onto nanoparticulate silica particles, i.e. PtTFPP/SiO₂, is produced and used in a filament which is then 3D printed as O₂-sensitive indicator dots (1 cm diameter, 30 μm thick) on a polyethylene terephthalate (PET) supporting film substrate. Two different filaments, prepared using the polymers, low density polyethylene (LDPE) and polylactic acid (PLA), respectively, are used to produce 3D printed PtTFPP/SiO₂/LDPE and PtTFPP/SiO₂/PLA O₂-sensitive indicator dots, with dynamic ranges of 0–30% and 0–400% O₂, respectively. The O₂ response characteristics of these two, very different, indicator dots, such as sensitivity, response time and temperature sensitivity, are measured and compared with those of a commercial O₂ indicator, FOSPOR (OceanInsight) and other commercial O₂ indicators. The potential of this method for mass manufacture of O₂ indicator dots and the likelihood that it can be extended to produce other optical indicators, such as those for ammonia or CO₂, are discussed briefly.