A piezoelectric unit, preferably a piezoelectric foil, is arranged in a medical plaster unit for therapeutic or stimulating influence of body tissue in an area underneath the plaster unit. First and second ground electrodes and a hot electrode are disposed on the buffer layer, the first and second ground electrodes being spaced either side of the hot electrode, the hot electrode and the first ground electrode being proximate to at least apart of the respective waveguides. It further comprises constructing a principal components analysis model from the data, wherein a weighting factor is applied to at least one of the data variables in the acquired data. The storage capacitor stores image data provided to the LC element through the driving controlling switch. After the time slots are reserved, the source node send optical time slices carrying services periodically at reserved time slots.