Electromagnetic Wave Sensors for Noninvasive Blood Glucose Monitoring: Review and Recent Developments

Diabetes is one of the most persistent and common immedicable diseases characterized by elevated levels of blood glucose, rendering the early detection and diagnosis of diabetes utmost important. Irrespective of currently available invasive and minimally invasive techniques, the noninvasive glucose measurement has drawn a lot of attention in recent years and continues to open up new areas for further research. This article provides a comprehensive overview of the developments over the last decade in the area of noninvasive blood glucose monitoring research, with particular reference given to the use of radio frequency electromagnetic (EM) wave for blood glucose sensing. The majority of the glucose sensors described in this article have been proven to be reliable by Clarke error grid analysis or similar methods but, amid all other known challenges such as reproducibility, specificity, and sensitivities, these glucose sensors were based on an expensive vector network analyzer (VNA). Finally, we conclude with a positive note that the noninvasive blood glucose monitoring research is beginning to be acknowledged not only on a global scale but also in applied physics and biomedical fields; however, more research is needed to overcome the challenges related to hardware alternative to a VNA and system integration involving enhancement of specificity and sensitivity.