A single wire large-area filament emitter for spectroscopic ethanol gas sensing fabricated using a wire bonding tool

Non-dispersive infrared (NDIR) gas spectroscopy is a highly accurate optical gas sensing technology, which has been implemented in various industrial applications. However NDIR systems remain too expensive for many consumer and automotive applications. The cost of the infrared (IR) emitter component is a substantial part of the total system cost. In this paper we report of a single filament IR emitter that is fabricated using wire bonding technology. Our fabrication approach offers the prospect of a fully automated assembly by means of utilizing a wire bonding tool to integrate the single filament to the MEMS structured silicon substrate. An application-specific wire bond trajectory enables the mechanical attachment of the filament to form the meander-shaped emitter with a total area of 1 mm
²
. The fabricated IR emitter utilizes a Kanthal (FeCrAl) filament with very high thermal stability and excellent emitting properties under atmospheric conditions. The packaged IR emitter has been characterized using Fourier transform infrared (FTIR) spectroscopy to study the emitted IR spectrum with respect to the requirements of NDIR systems.