US Patent 10401082 Tracking of sample boxes using energy harvesting

In one embodiment, a freezer system has one or more shelves, each shelf has shelf electronics and can receive one or more racks, each rack has rack electronics and one or more cells for receiving one or more boxes of samples, each box has one or more RFID tags. Freezer electronics communicate with the outside world and with each set of shelf electronics. Each set of rack electronics communicates wirelessly with the corresponding set of shelf electronics and with the corresponding box RFID tags. Power for the rack electronics is derived from wireless signals from the shelf electronics. The freezer system can detect the presence of racks on shelves and boxes on racks to track the location and the orientation of each received box.