A deflected edge emission field effect transistor (DEEFET), a hybrid solid-state and vacuum microelectronics device, was constructed with electron-beam lithography to measure magnetic fields. The fabricated DEEFET device employs an extremely sharp emitter tip, a pair of gate electrodes, and a pair of split anodes. Field emission currents were observed around an anode bias of 40 V without gate bias. As the gate potential was increased, a lower turn-on voltage (around 25 V) and a higher field emission current were observed. A comparison of the anode and gate currents showed that most of the emitted electrons are collected by the anode, and only a few electrons are lost to the gate electrode. When forward and reverse magnetic fields were applied, an emission current imbalance was measured due to electron deflection by the Lorentz force. The calculated magnetic sensitivity was 98%/ tesla for a forward magnetic field of 0.5 T and 92%/ tesla for the reverse magnetic field. These magnetic sensitivities are up to six or seven times higher than those from a conventional silicon-based magnetic sensor with a split drain. (C) 2004 The Electrochemical Society.