Design of finger-probe holder for continuous non-invasive blood glucose monitoring device for intensive care unit

Abstract

Near-infrared (NIR) spectroscopy is a promising technique for non-invasive blood

glucose measurement. Specific wavelength of NIR light is known to be sensitive to

glucose absorption. In this project, NIR light is directed via an optical probe onto the nail bed. The NIR light penetrates the nail and tissue and is then absorbed. The diffused light is collected and returned to a photo-sensor. The returning light carries glucose absorption information which is then analyzed and a model is developed for prediction of

concentration of blood glucose in the specimen. In the hospital intensive care unit (ICU) there is a need to tightly control blood glucose level of critically ill patients. Studies showed that tight glycemic control reduces mortality rate in the surgical ICU. Fluctuation of glucose for these patients can be drastic and fast changing. Hence, the need for a continuous non-invasive glucose monitoring system. However current technology at GlucoStats System focuses on development of discrete monitoring of blood glucose level. Hence the objective of this project is to design a finger-probe holder for continuous monitoring of glucose absorption non-invasively. One main source of error during measurement is the relative position change between measurement site and the optical probe which carries the NIR light. Relative position change can be caused by inherent movement of the finger and nail-bed. The finger's natural movement without conscious intention can be as high as 73 um. It was found that the finger natural movement can be nullified by using a flexible probe that moves together with finger's micro movement, thus resulting in zero relative position change.