Near-zero-power infrared relay based on microfluidic switch and metamaterial absorber

Internet of Things sensor nodes, which integrate information acquisition, processing, exchange, and execution modules, have widely been used for unattended industrial production, environmental monitoring, and other fields. However, limited battery power constrains the lifespan of the sensor nodes. In this paper, we propose a near-zero-power infrared relay consists of microfluidic switches and a metamaterial absorber (MA). When target appears, the MA absorbs the infrared energy emitted from the target and uses it to turn on the microfluidic switch. When valid information is not present, the microfluidic switch is in "off" state with a high resistance of over 109 ?. The infrared relay with a pair of microfluidic switches shows common mode suppression capability against environmental temperature variation. We further demonstrate a sensor node consists of the infrared relay and a MoS2 photodetector. In a standby mode, the sensor node shows near-zero power consumption. As target infrared signal occurs, the photodetector is wakened by the infrared relay and illustrates excellent optical sensing performance. The simplicity of this approach provides a route for significantly extending the lifespan of sensor nodes powered by batteries, especially the sensor nodes for detecting infrequent but critical events.