Development of Accelerated Life Testing Apparatus for Light-Emitting Diode Therapy

In conventional accelerated life tests (ALTs) used for lifetime assessments, a random time is selected to identify the point at which the LED degrades. In existing online testing systems, it is difficult to maintain the temperature of the measuring device at room temperature. Hence, it is difficult to ensure the accuracy and continuity of experimental values. Therefore, an improved life assessment apparatus is proposed in this paper. The proposed apparatus was designed to maintain the temperature of the photodiode, which measures the light output of the LED, by flowing coolant inside. An ALT was performed for five medical LEDs to verify the utility of the developed apparatus. During the 1100-hour ALT, the temperature of the diode was maintained at an appropriate value of approximately 25 °C, which proved that the proposed apparatus enables the real-time observation of the light intensity of LEDs, thereby improving the continuity and accuracy of experiments.