A Point-of-Care Device for Measuring Glucose,ketones,hemoglobin, and Glycated Hemoglobin From Whole Blood

Abstract

Point of care blood glucose meters and test strips are utilized by millions of individuals multiple times daily. Unlike clinical laboratories which analyze plasma samples for a true glucose value, POC devices use whole blood. Whole blood values can differ from plasma values by as much as +/- 20% of glucose concentration values. Aside from utilizing whole blood for glucose measurements, the biosensor test strips use embedded electrodes, and enzymes such as glucose oxidase and glucose dehydrogenase.The glucose measurements using these test strips are further affected by free oxygen, and the presence of other electroactive species in the blood sample. Biofouling of the test strips by materials such as proteins and chloride ions in blood further compromise the accuracy and precision of glucose measurements. This study presents an alternative detection system to the test strips and glucose meters currently on the market. We incorporated a three-layer paper microfluidic device to separate blood cells and proteins from smaller molecules such as glucose and ketones in a layered system using filtration. We developed assays to measure the concentrations of glucose, ketones, and red blood cells. We envision, once fully developed, these paper microfluidic-based assays will accurately and precisely quantitate glucose and ketone concentrations. Using the red cell count, calculations of the hemoglobin, hematocrit, and glycated hemoglobin (A1C) will be made. The glucose meter will possess a CCD camera for quantitation of each sample, and compare the sample concentrations to that from programmed standard curves. In our laboratory studies, we were able to perform the standard curves for glucose, glucose oxidase, and ketones. The results of our work was inconclusive due to the lack of a material holder for the spectrophotometer we were utilizing, which would have measured the fluorescence of the individual testing areas that had been pre-spotted with the corresponding fluorophores. However, proof of concept for separation of blood cells from plasma was demonstrated. Future work will include repeating the previous methods using a material sample holder on a spectrophotometer, and the fabrication of the paper microfluidic devices using a laser cutter, a wax printer, and a laminator.