Temperature-Independent Near-Zero Power Flame Detector Based on MEMS Photoswitch

SummaryThis paper reports on the first demonstration of a near-zero power flame detector with a consistent detection accuracy and a wide operating temperature range (−35°C to 85 °C) that satisfies industrial applications. The core sensing element of the flame detector is a plasmonically-enhanced micromechanical photoswitch (MP) that harvests infrared (IR) energy from a hydrocarbon flame through a spectrally-selective IR absorber to generate a wake-up signal without relying on active electronics (hence zero standby power consumption). The temperature compensation is achieved through passively tuning the detection threshold with a temperature-dependent bias voltage (2.70 – 4.37 V) applied to the open-circuit MP hence preserving the near-zero standby power feature. Furthermore, the required voltage values corresponding to the changing ambient temperature are decided based on a self-check of the pull-in voltage of a pre-calibrated device, which saves the need for a temperature sensor that would increase the cost and power consumption. Thanks to such a temperature compensation mechanism, the flame detector prototype shows an x19 improved stability compared to our previous demonstration.