A biosensor with a microfluidic structure surrounded by an electrode and methods of forming the electrode around the microfluidic structure of the biosensor are provided. A method includes forming a gate or electrode in a first layer. The method further includes forming a trench in a second layer. The method further includes forming a first metal layer in the trench such that the first metal layer is in electrical contact with the gate or the electrode. The method further includes forming a sacrificial material in the trench. The method further includes forming a second metal layer over the sacrificial material and in contact with the first metal layer. The method further includes removing the sacrificial material such that a microfluidic channel is formed surrounded by the first and the second metal layers.