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首页> 外文会议>2017 32nd Symposium on Microelectronics Technology and Devices >Graphene oxide nanofilm based surface acoustic wave sensor for fast measurements of water activity
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Graphene oxide nanofilm based surface acoustic wave sensor for fast measurements of water activity

机译：基于氧化石墨烯纳米膜的表面声波传感器，用于快速测量水活度

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摘要

Water activity (Aw) in different food products is normally measured by the measurement of the partial pressure of water vapor in the enclosed ambient with the sample to be evaluated placed inside. These measurements are done by monitoring the dew point temperature or by the measurement of the resistance of the special chemiresistor. We introduce the new method of Aw measurements for food industry based on the use of the surface acoustic wave sensor with the graphene oxide nanofilm as the sensitive element. The value of Aw is extracted from the time curve of desorption of water molecules from the product (kinetic curve) approximated by the sum of two exponents with different amplitudes and time factors, with one exponent (the fastest) having the saturation time much smaller than the other. It is proposed to use for calibration of the amplitude and time factor only of the fastest exponent after LSQ-fitting of the experimental curve to the sum of two exponents. This algorithm, omitting the use of the slow exponent, allows one not to wait until the complete thermodynamic equilibrium is reached. The proposed method gives the maximum discrepancy with the measurements by the commercial equipment on the order of 1-3%, having at the same time the average time of measurement 2-5 times smaller. This discrepancy can be adjusted to much smaller values introducing thermal stabilization of the measurement ambient. The results of experimental verification of the proposed method for large group of products are presented. Due to the high speed of measurements the proposed method could be used in the food industry for in-line Aw monitoring.
机译：通常通过测量封闭环境中水蒸气的分压来测量不同食品中的水分活度（Aw），将要评估的样品放入其中。这些测量是通过监测露点温度或通过测量特殊化学电阻器的电阻来完成的。介绍了基于以氧化石墨烯纳米膜为敏感元素的表面声波传感器的食品工业Aw测量的新方法。 Aw值是从水分子从产物中解吸的时间曲线（运动曲线）中提取的，该时间曲线近似于两个幅度和时间因子不同的指数的总和，其中一个指数（最快）的饱和时间比饱和时间小得多。另一个。建议将实验曲线与两个指数之和进行LSQ拟合后，仅将最快指数的幅度和时间因子用于校准。该算法省略了慢指数的使用，使人们不必等到达到完整的热力学平衡。所提出的方法与商用设备的测量值之间的最大差异为1-3％，同时平均测量时间要短2-5倍。可以将这种差异调整为较小的值，从而引入测量环境的热稳定性。提出了针对大组产品的方法的实验验证结果。由于测量速度快，因此所提出的方法可用于食品工业中的在线Aw监测。

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