Andrew Mills and Mark Thomas
A general method of preparation of thin-film sensors for O2, incorporating the dye ion-pair tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ditetraphenylborate, in a variety of different thin film polymer/plasticizer matrices is described. The sensitivity of the sensor depends upon the nature of the polymer matrix and plasticizer. A detailed study of one of these systems utilising the polymer poly(methyl methacrylate), PMMA, is reported. The sensitivity of this O2 sensor depends markedly upon the plasticizer concentration and is largely independent of temperature (24.5–52.5 °C) and age (up to 30 d). When exposed to an alternating atmosphere of O2 and N2, a typical oxygen film sensor in PMMA exhibits a 0–90% response and recovery time of 0.4 and 4.5 s, respectively.