Sensing on a Zero Power Budget

　　Sensing on a Zero Power Budget

　　简化物联网传感器

　　在任何时候，大部分的物联网都可能无所作为。物联网传感器通常只需要在很短的间隔内进行测量，然后将产生的少量数据送回收集器，然后返回尽可能少的电量，直到下一次测量为止。一些智能传感器可以由一个小电池供电，并在几年内不用充电或更换。

　　如果完全可以避免永久连接电源的需求，传感器可以无限期地部署，并且可以变得更小、更轻。这为新类型的传感器创造了机会，例如可以佩戴舒适的无损伤医用传感器。附着在皮肤上的无线温度感应贴片，可以快速检查，使佩戴者比有线传感器更能自由移动。与可重复使用的含铅传感器相比，一次性贴片也有卫生效益。

　　许多其他应用程序可以受益于粘贴传感器补丁，如监测温度，湿度或压力。它们还可用于占用检测、工业过程无连接监控或智能农业，如监测土壤或温室环境，或检查牲畜的体温。

　　A new category of smart sensors is emerging that combine an ultra-low-power sensor with RFID technology. These sensors can be powered by the energy in the RF field emitted by the RFID reader only for the time required to take a reading. Batteryless sensors such as these collect data and forward it to the reader only on demand， and do not take measurements or store data independently.

　　Figure 1 presents a simplified overview of the functional blocks of a passive patch sensor， including the front-end interface to an analog or digital transducer， signal conditioning， data processing， wireless communication， and power management. Integrating these various elements to create a system capable of operating with the limited available RF field energy demands skilled low-power design， with careful attention to computational load and efficient power management. Such a sensor must also be small and flexible for easy positioning， and comfortable if it is to be a wearable device such as a bio sensor.