# Smart Hydroponic Cultivation System for Lettuce
## 1 Introduction
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Ref.** & \begin{tabular}{c} **Cultvation** \\ **Technique** \\ \end{tabular} & **Tested Crop** & **MCU** & \
\begin{tabular}{c} **Monitored** \\ **Variables** \\ \end{tabular} &
\begin{tabular}{c} **Control** \\ **Mechanisms** \\ \end{tabular} & **Visualization** \\ \hline
[18] & Aeroponics & Spinach & \begin{tabular}{c} Wemos D1 \\ mini \\ \end{tabular} & \begin{tabular}{c} Air temperature \\ (T), RH and light \\ intensity \\ \end{tabular} & \
\begin{tabular}{c} Peltier cells, fans, \\ water pump \\ and nebulizer \\ \end{tabular} &
\begin{tabular}{c} ThingSpeak \\ website \\ \end{tabular} \\ \hline
[20] & Aquaponics & Not specified & \begin{tabular}{c} NodeMCU \\ ESP8266 \\ and level \\ \end{tabular} & \
\begin{tabular}{c} T, RH, \(CO_{2}\), light \\ intensity, EC, TDS \\ and water \\ temperature (WT) \\ and level \\ \end{tabular} & Water pump &
\begin{tabular}{c} Web \\ application \\ \end{tabular} \\ \hline
[21] & Hydroponics & Blueberry & ATmega & \
\begin{tabular}{c} T, RH, \(CO_{2}\) and \\ water level \\ \end{tabular} &
\begin{tabular}{c} LED lights, fan, \\ water pump and \\ cooling system \\ \end{tabular} & LabVIEW \\ \hline
[23] & Hydroponics & Not specified & Raspberry Pi & \begin{tabular}{c} T, light intensity \\ and NPK \\ \end{tabular} & \
\begin{tabular}{c} Pumps, video \\ camera and \\ LED lights \\ \end{tabular} &
\begin{tabular}{c} Android \\ mobile app \\ \end{tabular} \\ \hline
[24] & Hydroponics & Not specified & ESP32 & \begin{tabular}{c} pH, TDS, EC, WT \\ and level \\ \end{tabular} & \
\begin{tabular}{c} Water and \\ nutrient pumps \\ \end{tabular} &
\begin{tabular}{c} Mobile \\ app (Blynk) \\ \end{tabular} \\ \hline
[25] & Aeroponics & Not specified & \begin{tabular}{c} Raspberry Pi \\ (Node-RED) \\ \end{tabular} & \begin{tabular}{c} T, EC, TDS, energy, \\ WT and level \\ \end{tabular} & \
\begin{tabular}{c} Pumps, spray \\ nozzles and \\ LED lights \\ \end{tabular} &
\begin{tabular}{c} Web app with \\ NODE RED \\ \end{tabular} \\ \hline
[26] & Hydroponics & Lettuce & NIDO ONE & T, RH, pH and EC & \
\begin{tabular}{c} Recirculation \\ pump \\ \end{tabular} &
\begin{tabular}{c} Mobile app \\ with \\ NIDO PRO \\ \end{tabular} \\ \hline
[28] & \begin{tabular}{c} Hydroponics \\ (Nano bubbles) \\ \end{tabular} & Not specified & \begin{tabular}{c} Arduino Uno, \\ ESP32-E, \\ NodeMCU \\ ESP32-E \\ \end{tabular} & \
\begin{tabular}{c} T, dissolved \\ oxygen, TDS, pH \\ and WT \\ \end{tabular} &
\begin{tabular}{c} Nano bubbles \\ generator \\ \end{tabular} & Web app with \\ NODE RED \\ \hline
[29] & Hydroponics & Spinach & \begin{tabular}{c} Arduino uno, \\ Raspberry \\ Pi 4 \\ \end{tabular} & \begin{tabular}{c} T, RH, pH, TDS \\ and EC \\ \end{tabular} & \
\begin{tabular}{c} Nutrient pump \\ and LED lights \\ \end{tabular} &
\begin{tabular}{c} Web app with \\ NODE RED \\ \end{tabular} \\ \hline
[31] & \begin{tabular}{c} Hydroponics \\ (DWC) \\ \end{tabular} & Not specified & \begin{tabular}{c} NodeMCU \\ ESP8266 \\ \end{tabular} & \
\begin{tabular}{c} T, RH, pH and WT \\ \end{tabular} & Not specified &
\begin{tabular}{c} Web app and \\ What- \\ sApp alerts \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main features of the system used in [18; 20; 21; 23; 24; 25; 26; 28; 29; 31]. For each study, the corresponding reference is provided, along with the crop used to test the described system, the microcontroller implemented, the measured variables, the control mechanisms employed to keep those variables within the appropriate ranges, as well as the method used for data visualization. - cultivation system. All the information collected from the monitoring and control of these variables is transmitted to the cloud and made available to users for real-time visualization through a web application. Additionally, the system includes an automatic email alert mechanism--indicating a possible system failure.