There is provided a selectively permeable biointerface membrane, permitting selective diffusion of analyte therethrough, for use in an analyte sensor comprising a nanoporous substrate and a coating, on the nanoporous substrate, comprising a plurality of polymer chains whereby each polymer chain is attached at one chain end thereof to a surface of the nanoporous substrate. The receiver of the MIMO antenna system includes a window size decider and a beamforming weight selector. The fixing arm is provided with a plurality of first grooves.