Electrical Impedance Profiling of Plants, Coffee and TREO

Sammanfattning:  The aim of the project was to investigate the possibility of using low-cost hardware to monitor plant health, measure the impedance of water containing dissolved substances at different concentrations, and observe how the plant impedance is affected compared to auxiliary measurements of soil moisture, ambient light, humidity, and temperature.To measure impedance, we used electrical impedance spectroscopy which gives the impedanceacross a spectrum of frequencies. This gives a bigger data set than just measuring resistanceand a broader information on the thing being measured.Studying the electrical impedance characteristics of the plant Rosemary was one of the work's specific application-related objectives. This includes the calibration of the impedance measurement system and how the parameters change impedance measurement. We saw a need for a minimum voltage of at least 200mV for input voltage for measuring impedance. The averaging parameter was insignificant and so was the sampling amount. As the measurement sample did not have a resonance tank the settling could be as low as 10ms.Open compensation gave significantly better measurement at higher frequencies over 100kHz as this accounts for the shunt admittance in the circuit. Short compensation gave no significant improvements.For the measurement of coffee and TREO at different concentrations, we found that the impedance profile changes over the frequency sweep.Finally, the measurement of the plant impedance as it changes over time did not produce useful data because of connection problem between the Impedance Analyzer and the plant probes.