Abstract: A biosensor, a biosensor array, and an efficient method for simultaneously manufacturing a plurality of biosensors with improved reproducibility are provided. The method involves forming a sacrificial layer on a substrate. Next, a lower insulating layer is formed on the sacrificial layer, and a plurality of electrodes and electrode pads are formed on the lower insulating layer. An upper insulating layer is formed on the lower insulating layer with the plurality of electrodes and electrode pads, and a hard mask layer is formed on the upper insulating layer. After a portion of the hard mask layer and the upper insulating layer is etched to expose the plurality of electrodes and electrode pads, the remaining portion of the hard mark layer and the sacrificial layer is removed, so that the substrate is separated from the insulating layer.