A refrigerated appliance that dispenses items for use with a power source and includes a cooling system. The axial ridge increases in circumferential thickness towards the distal end of the conduit. A manifold comprising image representations and a statistical model of the manifold are used to correct the errors in the image. The insulator contact portion is located closer to the proximal end of the sensor element than a terminal contact portion at which the metal terminal contacts a corresponding one of the electrode pads. The variant current source is connected between the input terminal of the second trans-impedance and a ground terminal or a power supply source. Etching of the spacer creates a buried contact opening smaller than a lithographic minimum because silicon oxide surrounding the buried contact area is protected by the removable spacer.