Brian Dutra

Macro-scale acoustophoretic separation of lipid particles from red blood cells.

Autologous blood salvage is frequently used in cardiac surgery. However, shed mediastinal blood contains lipid particles ranging in size from 10 to 60 μm. Lipid emboli flow and subsequently lodge in the brain capillaries resulting in strokes, leading to neurocognitive dysfunction and death. A novel acoustophoretic filtration system has been developed to separate the lipids from the red blood cells (RBCs). The system works at the macro-scale, supporting flow rates in excess of 2 L/hr. The system is designed such that the acoustic radiation force is able to overcome the combined effects of fluid drag and buoyancy forces. Both RBCs and lipid particles are therefore trapped in the ultrasonic standing wave. Due to the opposite contrast factors of lipids and RBCs, the two components separate at opposite nodes within the standing wave, with lipids concentrating at pressure anti-nodes and RBCs at pressure nodes. Subsequent gravitational separation is used to separate the lipids and RBCs. Preliminary results were ...

A Novel Macro-scale Acoustic Device for Blood Filtration

Retransfusion of a patients own shed blood during cardiac surgery is attractive since it reduces the need for allogeneic transfusion, minimizes cost, and decreases transfusion related morbidity. Evidence suggests that lipid micro-emboli associated with the retransfusion of the shed blood are the predominant causes of the neurocognitive disorders. We have developed a novel acoustophoretic filtration system that can remove lipids from blood at clinically relevant flow rates. Unlike other acoustophoretic separation systems, this ultrasound technology works at the macroscale, and is therefore able to process larger flow rates than typical micro-electromechanical system (MEMS) scale acoustophoretic separation devices. In this work, we have first demonstrated the systematic design of the acoustic device and its optimization, followed by examining the feasibility of the device to filter lipids from the system. Then, we demonstrate the effects of the acoustic waves on the shed blood; examining hemolysis using both haptoglobin formation and lactate dehydrogenase release, as well as the potential of platelet aggregation or inflammatory cascade activation. Finally, in a porcine surgical model, we determined the potential viability of acoustic trapping as a blood filtration technology, as the animal responded to redelivered blood by increasing both systemic and mean arterial blood pressure.

A novel acoustic cell processing platform for cell concentration and washing

FloDesign Sonics has developed a technology to enable a single use (gamma irradiated) continuous cell concentration and wash application for manufacturing of cell-based therapies. The device has been designed to be able to process several liters of a suspended cell culture, e.g., T-cells, at concentrations of 1 to 10 M cells/ml. The cell suspension flows through the device and the acoustic radiation force field is used to trap and hold the cells in the acoustic field. After concentrating the cells, one or multiple washing steps are accomplished by flowing the washing fluid through the device, using the acoustic field to trap the cells while displacing the original cell culture fluid. The holdup volume of the device is about 30 ml. Results are shown for prototypes with a 1x0.75 inch flow chamber driven by 2 MHz PZT-8 transducers operating at flow rates of 1-2L/h, measured cell recoveries of 90% have been achieved with concentration factors of 20 to 50 for Jurkat T-cell suspensions, depending on cell concen...