No abstract

Foliar wetness plays an essential role in plant disease cycles and epidemic development yet no cost-effective leaf wetness sensors (LWSs) are available that could be deployed within large areas to better understand that role. Electronic LWSs comprise an artificial leaf and the electronic circuitry able to measure electrical impedance changes due to water film or drops on the leaf surface. We propose a simple, compact and low-cost electronic interface circuit (EIC) for artificial leaves based on capacitance changes. The circuit relies on the charge-transfer capacitive sensing method and it is implemented by a microcontroller unit (MCU), which offers computation and communication capabilities currently missing in commercial LWSs, This EIC can be used in custom and commercial artificial leaves hence suits studies that require a close emulation of particular plant leaves.

-We present the theoretical analysis and experimental performance results of a direct interface for capacitive sensors based on the charge transfer method when parasitic capacitances are included. The interface circuit implements a two-point calibration technique that makes measurement results independent from voltage-and temperature-dependent parameters. The measurement deviation is below 1 % FSR (Full Scale Range) for capacitances from 10 pF to 1 nF.