The present invention describes vertically stacked and hermetically sealed implantable pressure sensor devices for measuring a physiological signal. The implantable device comprises multiple layers, including a first wafer having a pressure sensor configured to measure the physiological signal and a second wafer having at least a digitizing integrated circuit. The first wafer is vertically stacked or disposed over the second wafer so as to form a hermetic seal. The device may include one or more additional layers adapted for energy storage and transfer, such as a third layer having a super-capacitor and a fourth layer having a thin film battery.
