Plant Biohybrid Hardware Setup Guide

Plant electrophysiology records surface electrical potentials from living plants. It does NOT indicate consciousness, sentience, or moral status. Plants lack a nervous system and are considered non-conscious. This module uses plant signals as an ethical, non-conscious biological input.

Components

• Ag/AgCl surface electrodes or conductive fabric electrodes
• AD620 instrumentation amplifier (or equivalent low-noise INA)
• Passive low-pass filter stage (cutoff around 5 Hz)
• Microcontroller with ADC (Arduino Uno or ESP32)
• Battery pack (no mains-powered frontend)
• Optocoupler or isolated USB interface
• Jumper wires, breadboard, shielded cable where possible

Connection Diagram

Plant leaf -> [Soft electrode] -> AD620 (gain ~1000) -> passive LPF -> Arduino ADC -> USB serial -> Computer

Safety Warnings

• Always use battery power for the plant-facing analog frontend.
• Use optical isolation before connecting to a computer.
• Never inject current into the plant tissue.
• Keep electrodes surface-level and non-invasive.
• Avoid pressing, puncturing, or damaging plant tissue.
• Stop immediately if the setup causes visible plant stress.

Minimal Arduino Driver (Pseudocode)

const int adcPin = A0;
const unsigned long sampleIntervalUs = 4000; // 250 Hz
unsigned long nextTick = 0;

void setup() {
  Serial.begin(115200);
  nextTick = micros();
}

void loop() {
  unsigned long now = micros();
  if (now >= nextTick) {
    int raw = analogRead(adcPin);
    float volts = (raw / 1023.0) * 5.0;
    float mv = volts * 1000.0;
    Serial.println(mv, 4);   // One channel CSV packet
    nextTick += sampleIntervalUs;
  }
}

For two channels, output comma-separated values:

Serial.print(mvCh0, 4);
Serial.print(",");
Serial.println(mvCh1, 4);

Plant Selection Notes

• Mimosa pudica: useful for observable rapid potential changes.
• Aloe vera: hardy, stable for longer bench sessions.
• Arabidopsis: common research model for reproducibility.

Practical Tips

• Let electrodes settle for several minutes before recording.
• Keep environmental conditions stable (light, airflow, touch).
• Log metadata (plant species, electrode position, humidity, time).
• Treat recordings as biological sensor streams, not mental-state data.