Gas Detector with Micromachined Chromium Gated Volcano Emitters

We propose a ionization source made up of an array of 10.000 micromachined silicon field emitter tips with chromium gate. Tips are used to produce and detect ions at atmospheric pressure using low applied voltages. These arrays of silicon tips are usually employed as high-vacuum field emitters where the gate is used to provide a high field, which is necessary to cause electron emission. In this application we used these devices at atmospheric pressure and studied the electric current generated from the field ionization process to identify the presence of gases in the test chamber. In the preliminary experiments on these devices several gases and vapors were tested. With acetic and formic acid, ions are mainly produced with the tips at a positive potential, while no current is measured for acetone, nitrogen, pentane and ethanol.