Decay time characteristics of La_(2)O_(2)S:Eu and La_(2)O_(2)S:Tb for use within an optical sensor for human skin temperature measurement

摘要

We focus on the development of a remote temperature sensing technology, i.e., an optical laser-based sensor, using thermographic phosphors for medical applications, particularly within an electromagnetically hostile magnetic resonance imaging (MRI) environment. A MRI scanner uses a strong magnetic field and radio waves to generate images of the inside of the body. The quality of the image improves with increasing magnetic resonance; however, the drawback of applying a greater magnetic strength is the inducement of heat into the body tissue. Therefore, monitoring the patient's temperature inside MRI is vital, but until now, a practical solution for temperature measurement did not exist. We show europium doped lanthanum oxysulphide (La_(2)O_(2)S:Eu) and terbium doped lanthanum oxysulphide (La_(2)O_(2)S:Tb) are both temperature sensitive to a low temperature range of 10-50 deg C when under ultraviolet (UV) excitation. The emission spectra and decay time characteristics of these phosphors were demonstrated. The results indicate that La_(2)O_(2)S:Eu has a quenching rate of (13.7 m deg C)~(-1) and (4 m deg C)~(-1) at 512 nm and 538 nm, respectively. In addition, La_(2)O_(2)S:Tb has a lower quenching rate of (4.19 m deg C)~(-1) at 548 nm due to its faster decay time.