A passive wireless impedance-loaded orthogonal frequency-coded (OFC) surface acoustic wave (SAW) sensor for wireless sensor networks was proposed in this paper. One of the chips on OFC SAW tag is connected to an external sensor, which could cause a phase shift in the time response of the corresponding part on the SAW device. The phase shift corresponds to the sensed quantity, which could be temperature, strain, vibration, pressure, etc. The OFC SAW tag is isolated by a proper package from the direct effect of the measurand on the device's response which could avoid the multiple measurands coupling. The simultaneous work of multiple sensors is guaranteed by orthogonal frequency coding. By processing the response based on an extended matched filter algorithm, sensing information of the specific coded OFC device can be extracted from the superimposed response of multiple independent encoded sensors. Compared to previous methods, the proposed method can produce a more flexible passive (battery-free) wireless sensor suitable for large-scale wireless sensor networks. Simulation and experimental results demonstrate the effectiveness of the sensor.

中文翻译：

---

用于无源无线传感器网络的阻抗加载正交频率编码SAW传感器。

提出了一种用于无线传感器网络的无源无线阻抗加载正交频率编码（OFC）表面声波（SAW）传感器。OFC SAW标签上的芯片之一连接到外部传感器，这可能会导致SAW设备上相应部件的时间响应出现相移。相移对应于感测到的量，可能是温度，应变，振动，压力等。OFCSAW标签通过适当的封装与被测物对设备响应的直接影响隔离开，可以避免多次被测物耦合。正交频率编码可确保多个传感器同时工作。通过基于扩展的匹配滤波器算法处理响应，可以从多个独立编码传感器的叠加响应中提取特定编码OFC设备的传感信息。与以前的方法相比，所提出的方法可以生产出适用于大规模无线传感器网络的更灵活的无源（无电池）无线传感器。仿真和实验结果证明了该传感器的有效性。