Provided is a pagewidth printhead having a plurality of micro-electromechanical nozzle arrangements. Each nozzle arrangement includes side walls located on a wafer substrate with a roof portion attached to said walls to define a printing fluid chamber. The roof portion defines an ejection port. Each nozzle arrangement also includes an inlet defined in the substrate to supply the fluid chamber with printing fluid, and at least one heater element having a mass of less than 10 nanograms suspended between the side walls in the fluid chamber. In operation, when electrical actuation energy of less than 500 nanojoules is applied to the heater element, the printing fluid undergoes thermal cavitation which increases fluid pressure in the chamber thereby ejecting printing fluid from the ejection port.