An apparatus and process for measuring the concentration of hydrogen gas being transferred through a nozzle from a source container to a destination container and for providing an alert andor taking action where hydrogen gas leaks may create an unsafe condition. The process includes polishing the back surface of the wafer, and depositing a thin polysilicon film on the polished back surface. Movement of the hot stick driving bar controls the movement of fixed and movable jaw portions of internal and external caliper measurement jaws. The brackets include a base member and a hinge arm pivotally attached to the base member. The cover has an inner surface having a coupling member attached thereto. Cleaning is effected by bringing carbon nanotube material into contact with an end face to create a differential adhesion in the proximity of the end face that more strongly attracts foreign matter residing on the end face to the carbon nanotube material than its attraction to the end face.