ELECTROLYSIS-BASED SYSTEM FOR GENERATION AND DELIVERY OF OXYGEN TO MICROFLUIDIC OXYGENATOR UNIT FOR PRETERM NEONATES WITH RESPIRATORY DISTRESS SYNDROME

Abstract

Respiratory distress syndrome (RDS) is a major cause of mortality and long-term morbidity annually affecting 14% preterm infants worldwide. Therapies have been developed to overcome this common disorder; however, limitations exist with these treatments that often lead to complications including bronchopulmonary dysplasia (BPD). One approach to address RDS is to implement a microfluidic oxygenator that serves as a respiratory support system for preterm neonates while the lungs fully develop, extra-uterine. This artificial lung assist device (LAD) is characterised by its non-invasiveness (given that it is connected via umbilical vessels), pumpless configuration, ambient air operation, portability and low priming volume. Furthermore, the LAD is formed by single oxygenator units (SOU) that are stacked in a parallel array which allows for usage on different body weights. The objective of this thesis is to design an electrochemical system to provide an in-situ enriched O2 environment able to supply 1.9 ml O2/min for use in the SOU while maintaining the simplicity of operation of the oxygenator. An inexpensive, electrically powered and compact device was envisioned allowing for a higher permeation flux to fully oxygenate the blood. Moreover, the system would be easy to manufacture, low maintenance and avoid the risk of gas contamination. In the initial work, different designs of electrolytic cells were developed and tested. The two- chamber design connected by a gel membrane showed an O2 production 10 times higher than with previous designs with 42 mg O2/L. Subsequently, different supporting electrolytes were tested. NaOH demonstrated a better performance and no degradation of the electrode in contrast to NaCl and Na2SO4. Stainless steel mesh (SSM) and graphite sheet electrodes were then tested; it was observed that stainless steel produced 3.4 times more dissolved oxygen (DO) than graphite with 28.3 mg O2/L. Experimentation with electrolysis of water showed that the DO in water reached stability 3 min after the electrolysis process was initiated measuring a change of DO of 29 mg/L at 3 A. Furthermore, an active oxygenation (AO) system was developed for in-vitro experiments via electrolysis of water and compared to a passive oxygenation (PO) system exposing blood to enriched O2 air and ambient air, respectively. It was demonstrated that AO provided 300% greater oxygenation to blood than PO. The electrolysis chamber designed for the microfluidic oxygenator allows the oxygenator to maintain its essential characteristics of simplicity and low cost while increasing the rate of oxygenation of blood. Preterm neonates suffering from RDS need an artificial lung that can partially support the oxygenation of their blood. Thus, combining the oxygenator with the O2 generation in-situ system enables a greater blood O2 uptake of 300% making possible the development of an efficient artificial lung.