Low-power gas sensors based on work-function measurement in low-cost hybrid flip–chip technology

To implement low-power gas sensors with low component costs, the principle of work-function read out via a hybrid suspended gate FET (SGFET) is being pursued, whereby a freely selectable sensor film undergoes a reversible work-function change corresponding to the build-up of a potential difference on the surface in response to gas adsorption/reaction. This is read out via an ISFET structure. An innovative design which allows cheap manufacturing will be described for the principle that has already been successfully demonstrated. The starting point of the design is a ceramic Al2O3 substrate coated with conductor patterns and sensitive materials onto which the FET is mounted in flip–chip technology. By means of the freely selectable sensor film and its preparation method, a wide range of applications can be opened up.