Agilent Technologies has received US Patent No. 6,994,429, "Printhead fluid supply system." The patent claims a printhead fluid supply system for use in ink-jet or pulse-jet type printers. According to the patent, a nanometer feature may be used as a pressure gauge to maintain desired pressure at a printhead. Additional features that may be used include a supply tubing setup configured to avoid introduction of air into a printhead as well as a system to replenish the printing fluid supply while the system is running.