In-vitro Assessment of the Adaptive Howland Current Source for Bioimpedance Haemolysis Measurements

Haemolysis, the rupture of red blood cells, is a significant concern that can occur at any stage during blood collection, transportation or handling. Haemolysed blood used for transfusions can lead to reduced oxygen saturation, inflammation, and renal dysfunction. Established methods for determining the haemolytic condition of blood involve visual inspection of the sample colour or the use of chemical reagents. There is a need for a method that would allow for in-situ detection of haemolysis in real-time without the need for specialised personnel or cumbersome facilities. While high-bandwidth bioimpedance has been proposed as a method for doing so, conventional portable instrumentation is limited in bandwidth (sub-MHz). This work presents whole blood bioimpedance measurements using the previously published Adaptive Howland Current Source (AHCS). Using a custom-designed electrode interface, in a tetrapolar square topology, blood samples were interrogated before and after lysis. Measurements taken with a commercial impedance analyser were found to be informative in determining haemolysis and were compared with measurements using the AHCS system showing satisfactory results up to 3 MHz.