Investigation of Anemia and the Dielectric Properties of Human Blood at Microwave Frequencies

Anemia is a condition that affects over 1.6 billion people worldwide untreated, the disease could lead to increased morbidity and mortality during pregnancy, affecting both the mother and the unborn child. This paper presents the measured dielectric properties of whole blood samples from 176 patients obtained from a hematology clinic; with 80 samples from male patients and 96 samples from female patients. Measurements were performed using a Keysight slim form probe and Keysight network analyzer to obtain the dielectric properties over a wide frequency range (500 MHz-8.5 GHz). A multiple linear regression analysis is performed to identify which components of the blood show the highest correlation with changes in the dielectric properties. Hemoglobin (Hgb) is shown to be the biggest predictor of changes in complex permittivity, demonstrating that permittivity measurements at a single frequency can potentially be used to detect anemia. A support vector machines algorithm is trained and tested to classify between blood samples from healthy patients and blood samples from patients with anemia. The classifier is optimized using a Bayesian-optimization approach during 10-fold cross-validation and then the average performance of the final trained classifier is evaluated through 10-fold testing on unseen data sets. Using a clinical definition of anemia defined as patients having a concentration of Hgb < 12.0g/dL, the trained classifier has an average sensitivity of 96.89% and specificity of 94.56%. These results demonstrate the potential for a low-cost resonant microwave device to be used to accurately detect the onset of anemia.