It is an object of the present invention to provide a data reproducer in which the quality of a reproduction signal is improved. The controller is further configured to incorporate the data in a data compilation representative of a set of measurements of the growth of the child for exportation of the data compilation via the data output port. The plasma grid assembly may include one or more plasma grids having slots of a particular aspect ratio, which allow certain species to pass through from the upper sub-chamber to the lower sub-chamber. Only one firing step is needed with a low peak firing temperature of about 700\xb0 C. The method can include retrieving contents of the buffer portion, and determining whether the contents contain the bit string.