A recently published study led by MIT’s Associate Professor Benedetto Marelli presents a microneedle system made of silk fibroin for targeted nutrient delivery and plant monitoring.
The technology was developed in collaboration with the Singapore-MIT Alliance for Research and Technology.
Inefficiencies in Traditional Agrochemical Application
Research shows that most agricultural chemicals applied by spray or dust do not reach the target crop. “Most of the active chemicals never reach their target leaves,” the study notes, often ending up in the soil and surrounding air instead.
Biodegradable Microneedles: A Scalable and Sustainable Delivery Method
The team developed hollow microneedles by pouring a salty silk mixture into cone-shaped moulds. Once dried and washed, the result is a biodegradable delivery system that dissolves safely in the plant. Made from silk fibroin—a protein extracted from silkworm cocoons—the needles are gentle on plant tissue and leave no residue in the field.
“Graduate students can make thousands of tips in an afternoon, with no clean room. It can be done outside of a clean room, you could do it in your kitchen if you wanted,” said Doyoon Kim, a former MIT postdoc.
Beyond ease of production, the microneedles offer a slow-release mechanism for nutrients, reducing the need for repeated applications and making them ideal for precision agriculture.
Nutrient Delivery and Crop Biofortification Results in Tomatoes
The silk microneedles were used to inject iron into nutrient-deficient tomato plants. After application, yellowing leaves turned green again, and there was no damage observed on the stems. The same system was used to deliver vitamin B12, with lab tests confirming the vitamin reached the fruit. These early results demonstrate both nutritional recovery and potential for crop fortification.
Real-Time Plant Health Monitoring Using Sap Sampling
Researchers tested the microneedles’ ability to collect sap from tomato plants during hydroponic trials. The system identified cadmium within 15 minutes of exposure.
“Current spectral cameras spot stress only after leaves go pale… Early warnings mean early fixes.” The microneedles remained in place for 18 hours, providing uninterrupted monitoring.
Automation Opportunities for Microneedle Field Deployment
The system is still in manual use, applied by researchers directly to plant stems. Future versions may use existing agricultural machinery for automated placement.
“There shouldn’t be a trade-off between the agriculture industry and the environment,” said Marelli. Field testing will soon begin on tomato plots in open-air conditions. Researchers will track yield, residues, and labour costs to assess commercial viability.
Cost-Effective Innovation with High Commercial Potential
Silk microneedles can be produced at low cost, with raw materials priced at only a few cents per needle. The manufacturing process uses reusable moulds and recyclable salt reagents, keeping overhead low. Researchers estimate that even a 5% increase in crop yield could allow greenhouses to recover initial investments in a single season. Investor interest is already growing, and discussions with seed companies are in progress.
The team is also exploring applications in reforestation, crop vaccination, and climate-resilient agriculture in Southeast Asia. “Ideas migrate when materials meet imagination,” said Marelli.