Design and testing of a thermoelectrically cooled portable vaccine cooler

Improper handling and the failure to maintain vaccines in a safe temperature range results in significant losses of vaccines in the rural developing world. This issue has reduced the success of immunization programs in the developing world, and consequently confidence in vaccinations. For vaccine refrigeration and delivery at the end stage of the cold chain, active thermoelectric cooling is a potentially viable alternative because the coolers are small and require few or no moving parts. A vaccine cooling system was constructed employing a Peltier-based thermoelectric chip (TEC) affixed to an aluminium block that holds the vaccine vials; a movable copper plate was interposed between the block and the TEC, acting as a thermal diode to prevent backflow of heat from the TEC into the vaccine holder. Heat was transported away from the hot side of the TEC to a remote heat exchanger. The aluminium block was contained in a heavily insulated plexiglass box equipped with a port on the top for transient removal of vaccine vials. With this cooler, vaccines can be maintained in the required temperature ranges of 4-8˚C for a conservatively estimated 10 hours at 37˚C on less than one full battery charge, while requiring less space than a common beach cooler. Since many parts of the rural developing world have sunny climates, the potential of the cooler’s power requirement to be partially supplied via solar panels was also evaluated.Bachelor of Scienc