Electrostatic Voltage Sensor Based on a High Aspect-Ratio Copper Actuator Levitating over a Small Air Gap

Conference: MikroSystemTechnik - KONGRESS 2009
10/12/2009 - 10/14/2009 at Berlin, Germany

Proceedings: MikroSystemTechnik

Pages: 4Language: englishTyp: PDF

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Dittmer, Jan; Brennecke, Alexander; Hecht, Lars; Büttgenbach, Stephanus (Institute for Microtechnology, Technische Universität Braunschweig, Deutschland)
Dittmer, Jan; Judaschke, Rolf (Physikalisch-Technische Bundesanstalt, Braunschweig, Deutschland)

A variable parallel-plate capacitor is fabricated in a micromechanical surface process with a high-aspect ratio actuator, reinforced by copper electroplating employing a sacrificial photo-resist layer. The device works as an RMS voltage sensor using the principle of electrostatic force. A copper layer with a coplanar waveguide below the actuator provides separated excitation and sensing electrodes. For low-loss electrical connectivity flip-chip technology is employed using solder paste. The presented design achieves a freely levitating plate area of up to 3x3 mm2 and an initial gap distance of only 1.5 µm. A pull-in voltage below 1 V at frequencies from DC up to 1 GHz and sensitivities up to 1 fF/mV are demonstrated.