Implementation of Battery-less Impedance Measurement System

The population of the planet is surging significantly, and it will hit 10.35 billion by the year 2100. Besides, there is an alarming level of hunger which is a major problem in developing nations, and the prevalence of hunger is particularly worrisome in Africa. We can simply say that the increase in population will create more demand for food. Each crop has great importance, and this is the main reason that scientists are looking for ways to monitor the health of the plant. Impedance analyzing of the plants is one of the possible ways to understand that. In literature, there are some ways to analyze the plant's impedance [1]. However, these are not easily applicable to the agriculture fields due to their high cost and volume. This thesis aims to propose a system with low power and small size that measures the impedance of the plants. The proposed system consists of a base station, tag, and interface. The firmware of the base station is designed to receive the data from the tag and deliver it to the interface. In the base station, the operations can be considered in two ways. The first way is calculating parameters such as light intensity in the base station. The second one is receiving the result of the measurement from the tag. In the end, both data packages are sent to the interface. The interface is designed for properly monitoring essential data such as the measured impedance of the plant, so the investigated plant's status health indicator. The sent data can be seen and saved by the interface for further analysis. The most crucial data is the impedance of the plant and that is harvested by utilizing the ultra-low power and battery-less tag. The tag sends a signal and measures the time of the operation. The time and the voltage drop are the two parameters that are necessary to estimate the impedance of the plant. The firmware of the tag and the base station are separately designed to keep their original operations but also be able to do the impedance measurement. Moreover, the theory behind the algorithm is rationalized step by step, and a practical approach is tested. Then the experiment was conducted to verify the proposed system. Also, known resistors were utilized to determine the limitations and calculate the accuracy of the system.