Abstract: A biosensor device includes a substrate plate, a metal conductive layer, a plurality of working electrodes and an insulating layer. The metal conductive layer is disposed over the substrate plate and has an upper surface. The working electrodes are disposed over the upper surface of the metal conductive layer, wherein each of the working electrodes has a top surface and each of the top surfaces is higher than the upper surface of the metal conductive layer. The insulating layer covers the metal conductive layer and surrounds the working electrodes, wherein an upper surface of the insulating layer is located between the top surfaces and the upper surface of the metal conductive layer such that the working electrodes protrude beyond the upper surface of the insulating layer. A method for manufacturing the biosensor device and a method for detecting biological molecules by using the biosensor device are also provided herein.