Posted in | Medical Sensor | Biosensors

Luminescent Zirconia to Sense Internal Body Temperature

A biocompatible white powder that is inexpensive and glows upon being heated could be helpful for non-invasive monitoring of the temperature of particular organs within the human body.

Internal organ temperature could be estimated following injection of a synthetic luminescent substance and targeted infrared irradiation, based on how long it takes for the photoluminescence to decay. Image Credit: © Tohoku University.

Researchers at Tohoku University performed initial tests to demonstrate the applicability of this concept. The study outcomes have been reported in the Scientific Reports journal.

Thermometers measure the temperature at the surface of the body. However, clinicians should be able to track and manage internal body temperatures in the case of certain critically ill patients, for instance, following heart attacks or head injuries.

So far, this has been performed usually by inserting a tiny tube into the blood vessels and heart. However, researchers have been seeking less invasive methods for monitoring temperature from within the body.

Takumi Fujiwara, an applied physicist at Tohoku University in Japan, and collaborators analyzed the prospective use of a white powder known as zirconia for this purpose.

Zirconia is a synthetic powder that is non-toxic, chemically stable, and easily accessible. Upon being heated, its crystals are excited and liberate electrons. Then, these electrons tend to recombine with “holes” in the molecular structure of the crystal. Through this process, the crystals start emitting light, or luminesce.

Since this material exhibits beneficial properties for use in the human body, the researchers intended to investigate and check whether it is feasible to use its luminescence to monitor the temperature.

Zirconia was heated by the research group using an ultraviolet lamp. They discovered that when the temperature of zirconia increased, its luminescence intensified. They noticed similar results by shining a near-infrared laser light on the material. This showed that it is possible to use both light and heat to trigger luminescence in zirconia.

Then, the researchers demonstrated that the luminescence of zirconia could be viewed with the naked eye by placing behind a piece of bone and illuminating with a near-infrared laser.

Collectively, the demonstrations indicate that zirconia could be potentially used to monitor core body temperature by injecting it and then illuminating a near-infrared laser light on a target site, for example, the brain. The longevity and intensity of the luminescence of the material will rely on the surrounding temperature.

While this fundamental study leaves some important issues unresolved, this work is a novel and promising application of [synthetic luminescent substances] in the medical field.

Study Researchers, Tohoku University

As a next step, the goal of the team is to devise a technique that makes the wavelength of luminescence from zirconia in the red to near-infrared region as it enables better transmissibility for human tissues. This could enable obtaining clearer information.

Source: http://www.tohoku.ac.jp/en/

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