this application uses technology found in existing patents u . s . pat . no . 7 , 823 , 394 and u . s . pat . no . 7 , 621 , 148b1 . the application solves the problem of internal icing within bio - sample storage freezers by introducing three new techniques to traditional mechanical freezers . highly effective hybrid insulation technique , internal purging using water vapor free air and close tolerance fitment of internal sub - assemblies .