Chemiluminescent detection of tear glucose on paper microfluidic devices

WHO Global Info Base declared that the number of people with diabetes in 2008 was 347 million that was doubled from 153 million in 1980. With rising obesity in global, concern has risen about prevalence of diabetes. Global estimates of mortality from diabetes will be dramatically increased in 2030. In fact, diabetes is one of important causes of mortality from cardiovascular and kidney diseases. Regarding vision power, severe ophthalmic complication such as cataract or retinopathy could be drawn from diabetes. These complications could lead to lose sight permanently. Therefore, early diagnosis and ongoing management is essential to ensure a healthy life for patients and avoid other diseases, such as blood circulation problems, kidney failure, heart disease, vision disease due to diabetes. The current methods of diabetes management rely on monitoring the glucose levels in the blood. The patients need to collect the blood drops at least four times a day and thousands times a year in invasive way to determine the glucose levels. In addition, There has been many reports of warning the invasive glucose sensor caused blood-related infections. Also, frequent invasive glucose measurements could result in the inadequate glycemic concentration as well as increased risk of hypoglycemia. Therefore, the development of glucose monitoring system with easy to use, convenient, cheap, and also non-invasive method is essential to self-monitor the glucose level and improve the quality of life of patients who require frequent glucose measurements. Approach for measuring the glucose concentration in body fluids, including alternative to urine, saliva and tears have tremendous potential for non-invasive diagnosis and management of diabetes. In comparison with other fluids, tear fluids are more easily accessible than blood and other interstitial fluids and have the benefits with consistent supply. The tear fluid is less sensitive in dilution than urine fluid. Previous studies applied a microfluidic technology to paper and measured glucose concentration in a non-invasive method using tears. Noh et al. quantified the colorimetric changes in glucose concentration using Photoshop’s grayscale program to unify the color changes in the limited sunlight when taking indoor illuminance. However, it is not easy to generalize the illuminance applicable to all situations. In the power usage statistics of 200 countries surveyed by the US Central Intelligence Agency (CIA) showed that in more than 100 countries around the world more than 1000 kW/year was consumed. On the other hand, where the 30 countries less than 0.1 kW/year was consumed. Turning on the 30 W bulb about 9 h per day for one year costs a power of about 100 kW. In 30 countries out of 200 countries, minimum power consumption is impossible. To those situated in such harsh conditions, it is difficult to measure the glycemic concentration using conventional paper based glucose sensors. Also, there are possibilities of the worst power outage by a sudden increase in power consumption even in the power supply sufficient country. For special situations such as in war training or in war, glucose measurements by conventional methods that require constant power supply are not easy. The purpose of this study was to investigate the chemiluminescent measurement of tear glucose and to attain quantitative tendencies of tear glucose without the need to be replaced by the specific gray-scale technique and no particular brightness conditions in order to be applied to all countries including the specific situations. This study sought to quantify the glucose concentration by using light-emitting reaction of luminol followed by the glucose oxidation. This study was to present the possibility of clinical application to measure glucose non-invasively with tears.