Master’s Thesis – ETH Zurich (GHE) / Tufts University (CEEO)
Bachelor’s Thesis – ETH Zurich (pdz)
For my Bachelor's thesis I conducted research in at the Product Development Group Zurich. In a recent study by Hugelshofer et al. it has been found that the presence and concentration of cell-free oxyhemoglobin (oxyHb) in CSF is likely to influence the occurrence of delayed ischemic neurological deficits (DINDs) after an aneurysmal subarachnoid hemorrhage (aSAH). Hemoglobin (Hb) is released from red blood cells (RBCs) into the surrounding cerebrospinal fluid (CSF) due to hemolysis. To measure and track the cell-free Hb concentration in the CSF, the study used manual sampling from the external ventricular drainage (EVD). They used the manual processing steps of centrifugation and spectroscopic analysis, based on which the Hb concentration could be determined. The pd |z, in collaboration with the University Hospital of Zurich (USZ) has proposed the use of a lab-on-a-chip device that automates this process. This is proposed in an effort to simplify the measurement and eventually allow continuous monitoring of Hb values without the need for sampling and time-consuming manual laboratory work. I have conducted systematic tests using centrifugation and microscale acoustofluidics for plasma extraction and subsequent measurement of oxyHb concentration by spectroscopic analysis. I compared these separation methods to assess the feasibility and reliability of using a microscale acoustofluidic chip versus centrifugation for such an application as part of the early development of an automatic continuous oxyHb measurement device. Separation by the microscale acoustofluidic chip yields slightly increased cell-free Hb values in the spectroscopic analysis. These are most likely caused due to a combination of contamination by sedimented RBCs from the system initialisation phase and some remaining and lysing RBCs from previous experiments, residing within the chip, the three-way switching valves and the connection caps, as well as potentially some limited hemolysis. However, these slight increases can be limited with some system adjustments and accounted for in future analysis. More research and development is necessary to improve, refine and validate the system. Considering the results of the experiments, the stable behaviour of the separation system and the future improvement possibilities, the viability of the project is promising.