On-chip fabrication of surface ionisation gas sensors

Microelectromechanical systems (MEMS) with integrated heaters, originally designed for the readout of the resistance of metal oxide (MOX) layers, were configured to observe surface ionisation (SI) gas signals. Interdigital platinum (Pt) electrodes on top of the dielectric membranes acted as ion emitting layers while flat-plate counter electrodes, positioned at a short distance above them, were used for the current readout. In this work, we show that this device configuration leads to SI responses orders of magnitude higher than those previously reported for thin-film, flat-plate devices and fully comparable to the performance of parallel-nanowire devices (PNDs). The high ionisation efficiency of our MEMS devices, which are suitable for large-scale production and further integration steps, is attributed to the electric field enhancement that takes place at the sharp edges of the Pt electrodes.