Feasibility of Microwave Dielectric Sensing to Monitor Potassium Concentration in Blood

Blood transfusion has been documented to cause hyperkalaemia due to changes in red blood cell membranes during storage. Hyperkalaemia is a common and possibly life-threatening electrolyte disturbance seen in individuals with chronic kidney disease and in those on renin-angiotensin-aldosterone inhibiting drugs for various medical conditions. These patients, as well as those hospitalized due to hyperkalaemic incidents, require regular monitoring of blood potassium levels. We aim to test the potential of dielectric sensing to monitor potassium concentrations in stored blood to better evaluate the risk of hyperkalaemia. The potassium ion concentration of a plasma mimicking solution, compound sodium lactate, was gradually increased from physiological 5 mmol/L up to 59 mmol/L by adding 0.5M potassium chloride solution using a micropipette. Results suggest that dielectric monitoring can be used to detect potassium changes in stored blood to assess the risk of transfusion related hyperkalaemia, with the conductivity showing measurable variations at lower frequencies. With further experimentation, dielectric sensing can potentially be developed for monitoring plasma potassium concentration in patients at risk of hyperkalaemic events or in those who are hospitalized, for better guiding their treatment.