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Team Members: Jon Klein Nguyen Vu Kyle Menges Christine Lowry Chris Stein Priya Narasimhan Julie Coggshall Week 4 Presentation: Selected Concepts Engineering Analysis Risk Assessment 2 Loops (R) Selection Criteria Weight Rating Easy to Operate 15% Ease of Implementation 1 Loop Rating Notes Rating Notes 0 -1 More valves to manipulate 1 Less valves to manipulate 8% 0 -1 Needs additional resistance -1 Needs compliance chamber volumes to be small for blood Maintainability 5% 0 1 Less subsystems make contact with Blood -1 More subsystems make contact with Blood Closed System Minimize Connections 15% 0 -1 More connecting points 1 Less Connection Points Amount Biocompatible 25% 0 1 Automated Resistance doesn't need to be biocompatible -1 Need to make Physiological Simulator biocompatible Volume (of liquid) 2% 0 -1 Requires extra tubing and valves 1 Requires less tubing and valves Space Required 5% 0 0 Same amount of large components 0 Same amount of large components Safety 10% 0 0 No additional risks or benefits 0 No additional risks or benefits Cost 15% 0 0 Cost of valves is small 0 Cost of valves/resistor is small Total Score Rank Continue? Notes 3 Loops 0.00 -0.10 -0.06 1 3 2 Yes Rank Subsystem 1 2 3 Tubing Tygon ABS Metal Resevoir Bags Gravity Driven Open Top Valves 3 Way Plastic 3 Way Stainless No Valves Compliance Tanks Elastic Material Membrane Tanks Resistance Pressure Cuff Servo Controlled Clamp Clamp Blood Extraction Three Way Valve Pressure Sensor Tubing Double Check Valve Pressure Sensors Intrusive Differential Intrusive Disposable Flow Sensors Ultrasonic Clamp-on Intrusive PTFE Suspended Transducer Temperature Sensors Thermocouple Infrared Temperature Control Heat Exchanger Hot Plate Water Bath Leak Test Tracer-Fluid Pressure Decay/Flow Bubble Test See Concept Selection Matrix for full analysis Resistance Calculations MeanArterial Pr essure MeanVenous Pr essure L Pr essure mmHg R Flow CariacOutput L min Source: Berne R. etal Physiology 4th edition Mosby, St Louis 1998 Tank size Calculations dV fluid Vtan k Atan k h fluid Vair Complance C dPfluid Pfluid gh fluid Pair Vair=Volume of air in tank = density of fluid Atank= Cross sectional area of tank g=Acceleration due to gravity Vtank=Volume of tank C= Compliance Pfluid=absolute pressure of fluid Pair=absolute pressure of air Source: University of Virginia Article, Design Initial testing of a mock human circulatory loop to test LVAD performance Risk Scoring Parameters Severity (choose most severe) Risk Ranking Likelihood 3 Highly Likely > 50% 2 Somewhat Likely 20% - 50% 1 Rare 0 - 20% Score level to Change Color: Likelihood Severity RPN Red 3 3 7 Yellow 2 2 4 Green 1 1 1 Product Project Injury Complete product failure, does not function Complete project Severe injury, failure potential death Meets some customer needs and specifications, product performs with less functionality than desired Moderate impact Treatment to budget required schedule Performance of product is not impacted No impact to project budget or Minor or no injury schedule Risk Item Summary Likelihood (1-3) Severity (1-3) RPN Total Number of 3's 2 3 62 Likelihood Severity Level Risk Priority Number Description/Comment Sensors Desired sensor accuracy not within budget 2 2 4 DAQ Dedicated DAQ system not within budget 3 3 9 Temperature Control Method for keeping constant temperature (98 deg F) not within budget 2 2 4 Controlling the flow restriction (resistance) using DAQ Resistance Automation not within budget 3 2 6 Compliance Specified compliance values not achieved 2 2 4 Specified resistance values not achieved 2 2 4 Temperature Human body temperature is not maintained 2 2 4 Viscosity Viscosity variation does not simulate human blood properties 1 2 2 Cost Physiological Resistance Simulation Likelihood Severity Level Risk Priority Number Biocompatibility Not all necessary components are biocompatible 2 2 4 Durability Valves, sensors, tubing degrade over time 1 2 2 Inaccurate measurements Pressure and flow measurements are inaccurate 1 2 2 DAQ Error Instrumentation and DAQ not communicating properly, DAQ does not collect or output data properly 2 3 6 Robustness System is not robust - variations in functionality and system output 2 2 4 Leak System or components leak causing error in measurement and/or contamination 2 2 4 Resistance Automation Flow restriction is not automated or does not function properly 1 3 3 Risk Item Materials Description/Comment Measurement Design