An exemplary printable composition of a liquid or gel suspension of diodes comprises a plurality of diodes, a first solvent andor a viscosity modifier. The blade and blade supporting structure are engagable along bearing contact locations that are spaced apart in a direction parallel to the axis so that the blade is stabilized both radially and axially as the knife operates. On the printed circuit board, there is a plurality of first pins, a first check pad and a second pad, wherein at least one first pin is electrically connected to the first check pad and at least another first pin is electrically connected to the second check pad. The adjusted image data is then communicated to a printhead of the device. The vent provides static pressure equilibrium between an ear canal and an ambient pressure.