Techniques to determine when to decrease a frame display rate based in part on the amount or degree of change between sequential frames. The semiconductor storage unit includes two or more semiconductor memories, a mounting board, and solder joints. The harvesting device comprises an analyte sensor positioned to be contacted by the harvested biological fluid and which generates a measurement signal representative of the analyte. The spring element 7 is moulded from a resilient polymeric material and comprises a plurality of C-shaped sections 7a angularly arranged in two interconnected stacks on opposite sides of the valve stem such that movement of the valve member 6 by means of a valve-operating member causes concurrent resilient deformation of all the sections.