All-Optical Temperature Sensing in Organogel Matrices via Annihilation Upconversion

Abstract

Modified organogels are bicontinuous colloidal systems which form a three-dimensional network embedding well-solvated organic dyes sensitive to minor changes in its microenvironment. It was demonstrated that these natural wax/oils based organogels can be applied for minimally invasive temperature sensing in life-science objects. The desired temperature sensitivity of better than 100 mK, centered around the physiologically relevant temperature of 36 °C, is warranted by using the process of triplet-triplet annihilation photon energy upconversion (TTA-UC) as a sensing mechanism. This all-optical sensing technique, based on ratiometric-type signal registration, ensures significant independence of the data obtained on excitation intensity instabilities, local molecular concentration fluctuations and field-of-view variations. The TTA-UC system is effectively protected for more than 1000 s against oxygen-induced damage, allowing stable performance of this temperature-sensing system even in ambient environments without lost of sensitivity and applying the same calibration curve.