The present invention relates to a method and an apparatus for producing a toothbrush comprising a handle and a brush head provided with a plurality of bristle bundles. The second plate member includes a first retaining surface that makes contact with the first friction member. The device includes a stem having a tip portion at one end and a base member at the opposite end of the stem. The center core includes at least one fiber Bragg grating with polarization-dependent reflectivity.