Spectroscopic hemoglobin and bilirubin measurement on optically opaque particulate fluids

Extracorporeal blood purification systems based on specific micro-adsorbents can be used for selective elimination of toxic substances from the patient. A suspension of blood plasma with micro-adsorbents is recirculated in the extracorporeal detoxification circuit. A safety system detecting erythrocyte damage by hemoglobin release as well as measuring the bilirubin elimination rate in the adsorbent circuit was developed. The sensor principle is based on broadband illumination and reflectivity measurement in the tubing where the adsorbent–plasma suspension is recirculated. From the specific reflection spectrum the hemoglobin and bilirubin content is calculated. Further, the effects of cross-sensitivity of hemoglobin and bilirubin on the detection accuracy are studied.