ELIJAH LI VICTOR MATEAS HODA RIFAI ROMAN STOLPER THEA ZIMNICKI Green Dot Technologies

Design Problem and Brief Pharmaceutical Storage Problems in Developing Countries:  Vaccine spoilage often occurs at vaccine provider’s site  Unreliable power grids  Untrained and overworked healthcare workers  Administration of spoiled vaccines = LOSS OF LIFE AND LIMITED RESOURCES We will design a refrigerator accessory which will:  Minimize cold loss during refrigerator usage  Minimize power consumption  Inform against administration of spoiled pharmaceuticals  Simplify inventory system

Physical Principles Goal: Retain Cold Temperature  Conduction  Thickness of materials  Thermal conductivity of materials  Convection  Decrease flow of warm air into fridge Dual layer Design of drawer Goal: Increase Energy Efficiency  Energy use related to internal temperature  Oscillation of cooling and non-cooling cycles used to keep temperature within acceptable range

SolidWorks Modeling Purpose  Physical model of prototype to build  Run thermal analyses  Extrapolate to other environments Next Step  Convection  Requires air flow rate  Empirically determined

Prototype Design

Prototype Design - Drawer

Temperature Optimization Designs Clamp  Tighter seal around door  Creates active role for user to avoid partial closure Magnetic Strip  Magnet on the drawer dividers to ensure drawer opens correctly  Helps user avoid leaving inside exposed to atmospheric conditions  Additional magnets on front panel of drawer  Helps hold drawer tightly to the front of fridge attachment

Management Designs Temperature Monitoring  Green LED lets the user know that the vaccines are in the optimal range and not at immediate risk  Red LED informs of spoilage  Temperature above 8 °C or under 2 °C  Yellow LED tells user to use vaccine as soon as possible  Temperature between 7 and 8 °C or 2 and 3 °C Inventory Mechanism  Allows user to avoid opening drawers unnecessarily  Vial’s weight presses metal conductors together to close one part of the circuit  User presses button to close second part of circuit  LED’s activated when entire circuit closed

Testing Power Consumption Test  Rewired energy meter to measure watts used Temperature Test  Used DAQ to measure temperatures of 3 thermistors over time Temperature Monitor  Used a microprocessor to output signal from 3 precise thermistors to an LCD  Will be used in prototype to output to LEDs

Proof of Principle Tests Purpose To show how temperature and energy use are related in a standard refrigerator To find conditions to isolate for potential improvement To compare prototype to a standard to show that goals have been met

Proof of Principle Tests Next Steps Determine flow rates for SolidWorks empirically using tubes and a pump to mimic air flow Run longer term tests Conduct same tests on all prototypes Compare efficacy of adjustments in prototype to capitalize on improvements

Next Steps Phase 1 1. Fabrication of Prototype Phase 2 1. Temperature and Power Consumption Testing on Prototype 2. Compare Results against Current Fridge Phase 3 1. Complete SolidWorks Model 2.Test and Implement Further Improvements

Acknowledgements Professor Sam Sia, Faculty Advisor Professor Gordana Vunjak-Novakovic Professor Elizabeth Hillman Keith Yeager Brenda Chen Dr. Timothy P Martens