Integrated Instrumentation System for Extracellular Electrophysiological Signal Acquisition in Amaranthus

Ndung’u R Wairimu, Riara Martin, Fidelis Ngugi, and Kamweru P Kuria
2026-11-12 1 views 0 downloads

 

Plant extracellular electrical signals are low-amplitude and susceptible to interference from the electrode–plant interface, recording electronics, and the surrounding environment. This study describes the development of an instrumentation system for recording extracellular electrical potentials in Amaranthus. The redesigned system incorporated an AD620 instrumentation amplifier, modified Ag/AgCl electrodes, an Anfatec USBLockIn 250 lock-in amplifier, and electromagnetic shielding. Although the lock-in amplifier was included in the signal-acquisition chain, synchronous detection of plant electrical signals could not be independently verified because no modulation or excitation mechanism was documented in the archived experimental records. Recordings were obtained from five plants subjected to alternating six-hour irrigation-withheld and post-irrigation periods over three consecutive days. The initial LF356N prototype and redesigned configuration were compared descriptively using the recorded mean, standard deviation (SD), signal dynamic range (SDR), normalized voltage range (NVR), and relative variability (RV). NVR decreased from 1.0367 to 0.1216, and RV decreased from 0.2992 to 0.0356. In contrast, SDR increased from 10.813 to 10.900 mV, while SD increased from 3.120 to 3.189 mV. The mean recorded potential shifted from −10.430 to 89.663 mV. Since NVR and RV are normalized by the absolute mean, their lower values do not independently demonstrate reduced electronic noise, improved accuracy, or increased sensitivity. Furthermore, the configurations were not independently calibrated or compared using known electrical inputs, and the available records do not establish matched test conditions. The irrigation-withheld and post-irrigation observations represent repeated measurements from the same five plants rather than independent biological replicates. Soil moisture and plant water status were also not measured. Overall, the findings are descriptive and highlight the need for further electrical and biological characterization of the instrumentation system.

 

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