An adjustable gathering chain assembly for a header of an agricultural harvester is disclosed as is a header including such an assembly and methods for adjusting the length of the gathering chain assembly. One flange of each panel extends over the flange of a neighboring panel atop the horizontal arm of a panel carrier. Upon applied voltage, capacitive actuators squeeze the composite, causing it to become conductive. Alternatively, vibrations of the membranous material can be produced by special vibration exciters or by means of ultrasonic coupling.