Sensing on a Zero Power Budget

　　簡化物聯網傳感器

　　在任何時候，大部分的物聯網都可能無所作為。物聯網傳感器通常只需要在很短的間隔內進行測量，然后將產生的少量數據送回收集器，然后返回盡可能少的電量，直到下一次測量為止。一些智能傳感器可以由一個小電池供電，并在幾年內不用充電或更換。

　　如果完全可以避免永久連接電源的需求，傳感器可以無限期地部署，并且可以變得更小、更輕。這為新類型的傳感器創造了機會，例如可以佩戴舒適的無損傷醫用傳感器。附著在皮膚上的無線溫度感應貼片，可以快速檢查，使佩戴者比有線傳感器更能自由移動。與可重復使用的含鉛傳感器相比，一次性貼片也有衛生效益。

　　許多其他應用程序可以受益于粘貼傳感器補丁，如監測溫度，濕度或壓力。它們還可用于占用檢測、工業過程無連接監控或智能農業，如監測土壤或溫室環境，或檢查牲畜的體溫。

　　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.