Gas sensor based on a metal oxide nanowire forest built on a suspended carbon nano-heater

Abstract

This paper reports a novel metal oxide nanowire (MOx NW) based gas senor built on a suspended carbon nanowire heater allowing ultra-low power consumption. This sensing platform was fabricated using only wafer level batch fabrication processes such as carbon-MEMS, atomic layer deposition, and hydrothermal growth processes. Owing to the mechanical rigidity, the suspended carbon nanowire allows selective circumferential growth of MOx NWs on its surface. The suspended carbon NW and MOx NWs are electrically separated with a thin HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layer. In addition, the suspended high-aspect-ratio geometry of the carbon NW enables MOx NWs to be heated with ultra-low power Joule heating. The architecture of the suspended nanowire forest ensures efficient gas access to the sensing sites, detecting NO2 as low as 100 ppb.