Abstract: An over-current protection device includes a resistor element, an outer electrode, and an encapsulation layer. The resistor element has a first insulation layer, a first electrically conductive layer, a PTC material layer, a second electrically conductive layer and a second insulation layer stacked sequentially from bottom to top. The first insulation layer has a. bottom surface and a first sidewall adjoining the bottom surface. The outer electrode has a first electrode and a second electrode disposed on the bottom surface. The first and second electrodes are electrically connected to the first conductive layer through the first and second vias, respectively. The encapsulation layer covers the first sidewall of the first insulation layer and extends to a part of the bottom surface, thereby forming a first perimeter on the bottom surface of the first insulation layer. The first and second electrodes are located inside the first perimeter.

Abstract: A gas sensor for sensing a gas in a humid environment includes a first electrode layer, a second electrode layer that is spaced apart from the first electrode layer, and a gas sensing layer that electrically interconnects the first electrode layer and the second electrode layer. The gas sensing layer is made of a hygroscopic electrically insulating material.

Abstract: A gas sensor for sensing a gas in a humid environment includes a first electrode layer, a second electrode layer that is spaced apart from the first electrode layer, and a gas sensing layer that electrically interconnects the first electrode layer and the second electrode layer. The gas sensing layer is made of a hygroscopic electrically insulating material.