Estimação do consumo de energia de sensores a onda de Love por simulação de circuito equivalente

Abstract

In recent years, surface acoustic wave (SAW) devices have been used as passive wireless sensors. This type of application presents, in addition to losses in the antenna and environment, losses related to the sensor itself, which limits the autonomy of the system. A Love Wave (LW) sensor is a type of SAW sensor that presents good results when applied to a liquid environment and can be used in remote measurement. In this sense, this work proposes the electric analysis of power consumption in surface acoustic wave sensors from the simulation of an existing equivalent model to estimate the active power consumption and efficiency of the sensor. Therefore, an equivalent circuit model of an LW sensor operating at 116.5 MHz was calculated from the characteristics of a real sensor. The equivalent circuit was simulated using LTspice® and its frequency response was obtained and compared with the measurements of the real sensor, showing a good match. Parameters like frequency and voltage amplitude and attenuation were variated and the simulation of a particular case with parameters fixed was performed. The results show that the consumption of the sensor is sensitive to the frequency and amplitude of the interrogation signal. The efficiency is sensitive to frequency and attenuation on the acoustic path. The results for the specific case show a consumption of about 1 mW and efficiency of 0.57 % when a 1.5 V signal at the resonance frequency is applied. The power consumption can be reduced by applying an interrogation signal with a frequency different from the operating frequency, but this method increases the insertion loss and suppress the acoustic response. Another way of reducing power consumption is through interrogation strategies like intermittent interrogation, which can reduce the average consumption. The results of this work contribute to the development of wireless interrogation systems aiming at the reduction of energy consumption.