Project Overview

The Automatic Seed Sprouter is a new Virtual Workgroups project to design and build a fully automated sprouting machine suitable for producing food-quality sprouts (broccoli, pea shoots, radish) for supply to restaurants and food businesses. The prototype uses a 20 cm food-grade stainless steel funnel with removable sieves, an automated water spray system, and a coin vibration motor to prevent seed coagulation.

An ESP32 microcontroller running MicroPython manages the entire sprouting cycle — monitoring and logging each spray event, tracking temperature and humidity inside the enclosure, and using a load cell to detect when seeds have absorbed sufficient water and sprouted. The operator can monitor and control the machine remotely via a built-in web dashboard.

Key System Components

💧 Water System

• 12 V DC normally-closed solenoid valve (food-grade body)
• Spiral full-cone stainless steel spray nozzle (316 SS, 1/8" BSP)
• 5 µm inline sediment filter and pressure-reducing valve
• YF-S201 flow sensor to confirm spray delivery and detect blockages
• DS18B20 waterproof temperature probe on the water supply line

⚖️ Sprouting Detection

• 1 kg load cell (TAL221) + HX711 ADC under the funnel support
• Configurable weight-gain threshold triggers the ‘sprouted’ state
• Minimum sprouting time guard prevents false detection from water pooling
• State machine: IDLE → SEEDED → SPROUTING → SPROUTED → HARVEST_READY

🌡️ Environmental Monitoring

• DHT22 / SHT31 temperature and humidity sensor inside the enclosure hood
• Optimal target range: 18–24 °C, 70–90 % RH
• Optional CO₂ sensor (MH-Z19) as an early indicator of microbial activity
• Light sensor (BH1750) to verify opaque cover is in place

💻 Firmware & Web Interface

• MicroPython on ESP32-WROOM DevKit — Wi-Fi connected
• Seed profiles stored in JSON on LittleFS (spray interval, duration, thresholds)
• Web dashboard: live state, temperature, humidity, weight, last spray time
• Manual controls: trigger spray, trigger vibration, initiate cleaning cycle
• Downloadable CSV event log for full batch traceability
• OTA firmware updates (IDLE state only)

Prototype Status

The prototype uses a Walfos 20 cm stainless steel kitchen funnel (304 SS, dishwasher-safe, with fine and coarse mesh sieves) as the sprouting vessel. Hardware has been specified and initial components sourced. The stainless steel prototype is currently under construction.

Estimated prototype batch capacity: 60–200 g dry seed yielding 300–700 g sprouts per 5–10 day cycle depending on seed variety.

Food Safety

All wetted components meet food-contact material regulations (EU 10/2011 / FDA 21 CFR). A citric acid passivation procedure is carried out on all new stainless steel parts before first use. A four-stage inter-batch sanitisation procedure (automated flush, manual wash, citric acid or H₂O₂ soak, final rinse) is defined and logged for every batch.