Development of minimally invasive and site-selective biological temperature sensing is quite importantin medical field. This study presents a novel temperature sensing technique based on afterglow and optically-stimulated luminescence (OSL). The dependence of afterglow photoluminescent intensity on the environmental temperature of zirconia (Zro 2 ) phosphor is examined to validate its use as a sensing probe. In addition, assuming the measurement in deep-part of human body, we have applied the information gathered from our validation to observe oSL from the Zro 2 by irradiation with near-infrared laser through a bone sample. This study demonstrates an alternative medical application of phosphor, and introduces an elemental-technology for the temperature sensing.Body temperature is main vital sign, which is closely related to immune system and metabolism. A technique for biological temperature monitoring is a powerful tool for medical treatment and monitoring human health. In addition, targeted temperature management has the potential to reduce the risk of brain dysfunction after a head injury and cardiopulmonary arrest. Although clinical thermometers and thermography are non-invasive, the methods measure the temperature on the surface of body. The gold standard for measuring temperature in critically ill patients is the Swan-Ganz catheter (Suppl. Fig. S1). The catheter must be inserted into the body in order to monitor the temperature at the desired location. Consequently, there is a need for accessible and minimally invasive temperature sensing methods which can monitor local internal temperature.Optical/spectroscopic measurement is recognized to be a minimally invasive and contactless method, and particularly, fluorescent and afterglow phenomena have been attempted to utilize for sensing-/imaging-applications so far 1-5 . Quantum-dots and fluorescent polymers have been proposed as temperature sensors for cell-imaging due to the relationship between temperature and fluorescence intensity/lifetime 1,2 . The observation of these effects is only possible with the magnification of a microscope. Chermont et al. developed a bio-imaging technique using afterglow phosphor of Eu 2+ , Dy 3+ , Mn 2+ -tri-doped Ca 0.2 Zn 0.9 Mg 0.9 Si 2 O 6 6 . Their study results inspired us to use the afterglow phenomenon to measure the temperature within the human body. In this manuscript, the fundamental measurements necessary to validate the use of the decay curve in the afterglow phosphor to measure temperature are presented. In addition, optically-stimulated luminescence (OSL) phenomena was also considered as irradiation of near-infrared (NIR) laser light would enable site-selective photoluminescence (PL), making it possible to obtain temperature information at internal sites in the human body.www.nature.com/scientificreports www.nature.com/scientificreports/ line. This departure was probably due to a partial electron-release from a deeper-trapping site corresponding to the peak F with peak at ~353 K. The pre-heating process is an eff...