The global demand for sustainable and nutritious food sources has never been more urgent. With rising populations, shrinking farmland, and the environmental toll of traditional agriculture, scientists are turning to microalgae—tiny aquatic organisms packed with protein, vitamins, and minerals—as a solution.
Microalgae are photosynthetic microorganisms that grow in freshwater or marine environments, converting sunlight and carbon dioxide into energy. Among these, Spirulina stands out for its rapid growth and exceptional nutritional profile.
Spirulina is a cyanobacterium (blue-green algae) known for its spiral-shaped filaments and ability to thrive in alkaline water. However, cultivating microalgae has historically required industrial-scale systems, making it inaccessible to ordinary households.
A groundbreaking study published in Computers and Electronics in Agriculture (2025) introduces the Smart Microalgae Incubator System (SMIS), a compact, IoT-powered device designed to grow Spirulina at home with minimal effort.
The Promise of Microalgae
Microalgae, such as Spirulina, are microscopic plants that thrive in water and sunlight. They are celebrated for their ability to convert carbon dioxide into biomass through photosynthesis, a process where light energy is used to synthesize nutrients from CO₂ and water.
This makes them a carbon-negative food source, meaning they absorb more CO₂ than they emit during production. For example, producing 1 kilogram of Spirulina absorbs 1.3 kilograms of CO₂, offering a dual benefit of nutrition and environmental repair.
Nutritionally, Spirulina is a powerhouse: it contains up to 70% protein by dry weight, along with essential fatty acids, fiber, and minerals like iron and calcium. These qualities make it a valuable supplement for vegetarians, athletes, and communities facing food shortages.
Despite these advantages, microalgae cultivation has largely been confined to large-scale farms or research labs due to the need for precise temperature, light, and nutrient controls.
Traditional methods, such as open ponds (shallow outdoor basins) or photobioreactors (closed systems with artificial lighting and temperature control), are either prone to contamination or expensive to operate. The SMIS bridges this gap by automating the entire cultivation process, bringing industrial-grade precision to kitchen counters.
Design and Functionality of the SMIS
The SMIS is a self-contained, IoT-enabled system that simplifies Spirulina cultivation into three main stages:
- growth monitoring,
- automated harvesting,
- nutrient recycling.
At its core is a 10-liter glass tank where Spirulina grows under controlled conditions. Sensors embedded in the tank continuously track critical parameters like temperature, pH (a measure of acidity or alkalinity), dissolved oxygen (DO₂), and total dissolved solids (TDS), which indicate the concentration of nutrients in the water.
For instance, the system maintains a temperature range of 23–30°C, ideal for Spirulina growth, and a pH of 8.3–9.0 to prevent bacterial contamination. A robotic arm lowers sensors into the water hourly to measure dissolved oxygen (4,000–5,000 ppm) and total dissolved solids (1,464–1,600 ppm), ensuring optimal nutrient balance.
Harvesting is triggered by a turbidity sensor, a device that measures the cloudiness of water caused by suspended particles like Spirulina. This sensor works by shining a light through a diluted sample of the culture—lower voltage readings indicate higher turbidity, signaling it’s time to harvest.
When activated, peristaltic pumps (devices that move fluid through tubing via rotating rollers) transfer 10% of the culture to a separate tank, where a 25-micron nylon mesh (a fine filter with pores 25 micrometers wide) filters out the biomass.
The remaining liquid is sterilized with UV light (ultraviolet radiation that kills microorganisms) and recycled back into the main tank, reducing water and nutrient waste by 90%.
Meanwhile, a fresh medium tank automatically refills lost water, ensuring uninterrupted growth. All data is uploaded to a cloud-based dashboard, a remote platform that stores and displays real-time information, allowing users to monitor progress via smartphones and receive alerts for maintenance tasks like refilling nutrients.
SMIS vs. Manual Cultivation
To evaluate the SMIS, researchers conducted a 125-day experiment comparing it to a manually managed control tank. Both systems used Zarrouk’s medium, a nutrient-rich solution specifically formulated for Spirulina cultivation.
This medium contains mineral salts like potassium phosphate, sodium bicarbonate (a carbon source), and sodium nitrate (a nitrogen source), which are essential for algae growth. Identical Spirulina strains were grown under similar light conditions.
The SMIS operated with 16 hours of daily LED light (4,644 lux), while the control tank had continuous 24-hour light (4,568 lux). Lux is a unit measuring light intensity, and the small difference (1.64%) ensured a fair comparison. Despite the shorter light cycle, the SMIS achieved comparable growth rates, producing 0.4686 grams of biomass per liter daily.
By day 60, the SMIS yielded 15.7 grams of Spirulina per liter, slightly less than the control’s 16.2 grams but with far less human intervention. Nutritional analysis revealed striking differences.
- Spirulina from the SMIS contained 69.1% protein, 10.3% crude fat, and 15.7% fiber—surpassing the control tank’s 66.1% protein, 5.5% fat, and 13.6% fiber.
Researchers attributed this to the SMIS’s stable environment and automated nutrient recycling, which reduced stress on the algae.
Minerals like potassium (vital for cellular function) and phosphorus (essential for energy transfer) were slightly lower in the SMIS (1.51% vs. 2.00% potassium), likely due to repeated medium recycling. However, the system’s closed-loop design reduced freshwater use by 20%, a significant advantage in water-scarce regions.
Challenges and Limitations
While the SMIS represents a leap forward, it is not without limitations. The initial setup cost—estimated at 500–700 for sensors, pumps, and UV lights—may be prohibitive for some households.
Energy consumption is another concern: sensors and cloud data storage increased electricity use by 15–20% compared to manual systems, with LED lights accounting for 60% of the total.
Sensor durability also proved problematic. Prolonged exposure to alkaline water caused sensor drift (gradual deviation from accurate readings) in pH and dissolved oxygen measurements after 90 days, requiring recalibration.
Additionally, the system’s small scale (10-liter capacity) limits biomass production, making it more suitable for supplements than full meal replacement.
Nutrient depletion in recycled medium posed another challenge. Nitrogen levels dropped by 12% over time, slowing growth in later stages. Nitrogen is a critical component of amino acids and chlorophyll, and its scarcity can stunt algae growth.
Researchers suggest periodic medium replacement or adding nitrogen supplements to address this. Despite these issues, the SMIS’s benefits—automation, water savings, and high-quality output—outweigh its drawbacks for home users.
Future Applications and Scalability
The study outlines several avenues for improving and expanding the SMIS. First, testing with other microalgae species like Chlorella (a green algae high in lipids) or Dunaliella (a salt-tolerant species used in beta-carotene production) could broaden its applications.
Customizing environmental controls for different species’ needs—such as adjusting pH or light cycles—would make the system versatile for diverse dietary and industrial uses.
Scaling the SMIS for commercial production is another priority. Researchers propose linking multiple units into modular arrays (interconnected systems that share resources), as illustrated in Figure 12 of the study, sharing control systems to reduce costs.
Bulk purchasing of sensors and shared cloud storage could lower expenses by 30%, making the system viable for schools, urban farms, or small businesses. Integrating artificial intelligence (AI) could further enhance efficiency.
Machine learning algorithms might predict optimal harvest times or adjust light intensity based on weather forecasts, boosting yields by 10–15%.
One of the most exciting prospects is combining the SMIS with air purification systems. Microalgae absorb CO₂ during photosynthesis, and studies show they can reduce indoor CO₂ levels by 55% when paired with ventilation systems.
This dual function—producing food while cleaning air—could make the SMIS a cornerstone of sustainable living in cities.
Conclusion
The Smart Microalgae Incubator System is more than a technological marvel; it’s a blueprint for sustainable living. By automating Spirulina cultivation, it empowers individuals to take control of their nutrition while reducing their environmental footprint.
Though challenges like cost and scalability remain, the SMIS proves that home-based microalgae farming is not only possible but practical. As climate change intensifies and food insecurity grows, innovations like the SMIS offer a path forward. They remind us that solutions to global crises can be as small as a speck of algae—and as close as our kitchens.
Power Terms
1. Microalgae Cultivation
The process of growing microscopic algae (like Spirulina) in controlled environments such as tanks or ponds. It is important for producing nutrient-rich food, biofuels, and reducing carbon dioxide. Example: Growing Spirulina in a home-based smart incubator.
2. Spirulina
A type of blue-green microalgae rich in protein, vitamins, and minerals. It is used as a dietary supplement, animal feed, and biofuel source. Example: Spirulina platensis cultivated in Zarrouk’s medium.
3. IoT (Internet of Things)
A network of connected devices (like sensors and pumps) that share data over the internet. In the study, IoT monitors temperature, pH, and controls algae growth automatically. Example: Sensors in the Smart Microalgae Incubator System (SMIS) send data to a cloud dashboard.
4. Smart Incubator
An automated system to grow organisms (like algae) under optimized conditions. The SMIS uses sensors, pumps, and lights to maintain ideal growth settings. Example: The SMIS adjusts light cycles and harvests algae automatically.
5. Turbidity
A measure of how cloudy water is due to particles like algae. High turbidity means more algae. The SMIS uses a turbidity sensor to decide when to harvest. Example: Voltage readings from the sensor indicate algae density.
6. pH
A scale (0–14) measuring how acidic or alkaline water is. Spirulina grows best in alkaline water (pH ~9). The SMIS monitors pH but doesn’t adjust it since the medium is pre-mixed.
7. Dissolved Oxygen (DO2)
The amount of oxygen in water, critical for algae growth. The SMIS uses a sensor to track DO2 levels. Example: DO2 drops if algae overpopulate or stop growing.
8. Total Dissolved Solids (TDS)
A measure of minerals and salts dissolved in water. High TDS can stress algae. The SMIS monitors TDS to ensure nutrient balance. Example: TDS ≈1600 ppm in the study.
9. Biomass
The total mass of living algae in a system. It is measured to track growth. Formula: Biomass (g/L) = 0.4686 × OD680 + 0.0907, where OD680 is light absorbance at 680 nm.
10. Zarrouk’s Medium
A nutrient-rich solution for growing Spirulina. Contains minerals like sodium bicarbonate and nitrates. Example: Used in both SMIS and control tanks in the study.
11. Photobioreactor (PBR)
A closed system for growing algae with controlled light, temperature, and nutrients. Example: Industrial PBRs vs. home-based SMIS.
12. Open System
Algae grown in open ponds, cheaper but prone to contamination. Example: Outdoor Spirulina farms.
13. Closed System
Algae grown in sealed tanks (like PBRs) to avoid contamination. Example: The SMIS is a small closed system.
14. Automated Harvesting
Using pumps and filters to collect algae without manual work. The SMIS harvests 10% of biomass automatically when turbidity signals readiness.
15. Nutrient Recycling
Reusing water and nutrients after harvesting. The SMIS sterilizes used medium with UV light and pumps it back into the tank.
16. Growth Rate
How fast algae biomass increases over time. Formula: Growth Rate (g/L/day) = (Final Biomass – Initial Biomass) / Days.
17. Protein Content
The percentage of protein in dried algae. Spirulina from the SMIS had 69% protein, higher than manual cultivation.
18. Crude Fat
Fat content in algae. SMIS-grown Spirulina had 10.3% fat, useful for dietary supplements.
19. Crude Fiber
Indigestible plant material. SMIS algae had 15.7% fiber, aiding digestion.
20. Carbon Sequestration
Capturing carbon dioxide (CO2) from the air. Microalgae absorb CO2 during growth—1 kg of algae absorbs 1.3 kg of CO2.
21. Linear Actuator
A robotic arm that moves sensors in/out of water to prevent damage. Example: The SMIS uses this to extend sensor lifespan.
22. Peristaltic Pump
A pump that moves liquid through tubes without contamination. Example: Used in the SMIS to transfer algae and nutrients.
23. UV Sterilization
Using ultraviolet light to kill bacteria in recycled water. The SMIS sterilizes harvested medium before reuse.
24. Dashboard
A user-friendly interface showing real-time data (temperature, pH) from the SMIS. Example: The cloud-based dashboard in Fig. 8.
25. Peer Review
A process where experts check research quality before publication. Example: This paper was reviewed before appearing in the journal.
Reference:
Chai, A. B. Z., Lau, B. Z., Ginjom, I. R. H., Tee, M. K. T., Show, P. L., & Palombo, E. (2025). Development of a smart incubator for microalgae cultivation in food production: A case study of Spirulina. Computers and Electronics in Agriculture, 233, 110163. https://doi.org/10.1016/j.compag.2025.110163“
