A backpack having a harness configured to be secured to the torso of a user, and a movable storage compartment pivotably connected at a first end to a first location on the harness. The first section is patient proximal when disposed in the patient’s rectum and has durometer hardness in the range of about 50 A to about 90 A. When the at least one sensor head is mechanically worn, a measuring signal is generated by the at least one sensor head or a change of a measuring signal, produced by the at least one sensor head prior to having been mechanically worn, is detected. The comparator generates an output signal representative of the comparation and the system comprises a logic block controlled by the output signal of the comparator. An oxide layer is deposited over the etch stop layer and within the isolation trenches. 5 to 20 bar and a gas hourly velocity of from 10 to 500 h\u22121 for from 0.