An impeller for use in conjunction with a percutaneously-insertable blood pump or other rotatable equipment includes a blade that is segmented into a plurality of overlapping or abutting bladelets. One of the proposed de-interlacing methods includes edge detection of a target region corresponding to a target position. Other embodiments are also described. In some embodiments, the subchannels may be detected with a parallel set of matched filters. In another alternative, all touch sensing elements can be between the color filter and array plates.