The invention relates to mechanically bi-stable shutter assemblies for use in display apparatus to form images. The invention ensures that inert gas dissolved in a liquid raw material can be removed easily and efficiently in a semiconductor manufacturing process using a liquid raw material. The present invention uses a recess in this unused section to accommodate and retain a writing utensil. The contoured actuation handle may be retained in the retaining slot to provide an action-open-position. The cluster analysis mechanism analyzes the augmented sensor data to determine the likelihood that compressor blade erosion has occurred.