A team of scientists from MIT and Singapore has come up with an innovative and eco-friendly way to take better care of crops—using tiny needles made from silk.
These microneedles can deliver nutrients, vitamins, and even monitor plant health, offering a more precise alternative to spraying chemicals, which often leads to waste and pollution.
Typically, when farmers spray pesticides or fertilizers on crops, only about half of the chemicals actually reach the plant.
The rest ends up in the air or soil, where it can harm the environment. To solve this, researchers developed hollow silk microneedles that can inject substances directly into the plant, ensuring that almost nothing is wasted.
The study was published in Nature Nanotechnology and led by Benedetto Marelli, a professor of civil and environmental engineering at MIT.
The project also involved researchers from the Singapore-MIT Alliance for Research and Technology (SMART), including Yunteng Cao and Doyoon Kim, who designed a new method to make these microneedles cheaply and easily.
Instead of needing expensive lab equipment, the team found a way to make them using silk protein mixed with salt in tiny molds.
As the water dries, the salt forms crystals that can be washed away, leaving behind a hollow space in each needle. This means the technique is simple enough to be done outside of high-tech labs, potentially even in a regular kitchen.
These microneedles are designed to pierce a plant’s tough outer layer without causing serious harm. In earlier work, the same team showed that silk microneedles could deliver small doses of chemicals and monitor plant pH.
But now, with their new hollow design, the needles can deliver much larger doses of nutrients and medicines. This is a big step forward for use in large-scale agriculture.
In tests, the researchers used their microneedles to treat tomato plants with iron to fight a disease called chlorosis, which turns leaves yellow and reduces crop yields.
The needles provided a steady supply of iron directly into the plant, effectively treating the condition without damaging the plants.
They also successfully added vitamin B12 into tomato plants—a nutrient not typically found in plants—which eventually reached the fruit. This could open up new ways to make fruits and vegetables more nutritious before they’re even harvested.
Aside from delivering nutrients, the microneedles can also monitor plant health. In one experiment, the team used the needles to detect cadmium, a toxic heavy metal, in tomato plants grown in contaminated water.
The needles absorbed the toxin in just 15 minutes, offering a fast and reliable way to detect harmful substances. They also tracked cadmium levels over 18 hours, showing how microneedles could help farmers keep an eye on crop safety in real-time.
Traditional methods to check plant health, like visual inspections or sap testing, are either too slow or only catch problems after they’ve already caused damage. These new microneedles could act as a real-time warning system, helping farmers take action before crops are seriously harmed.
Although the team applied the microneedles to plants by hand during the study, Marelli believes they could be attached to farm equipment or autonomous vehicles in the future to treat large fields quickly and efficiently. He sees this technology not as a replacement for all existing farming practices, but as a powerful tool to work alongside them, reducing chemical waste and environmental impact.
The researchers also note that their simple, low-cost method of making the microneedles could have uses beyond agriculture. They suggest it could be adapted for use in medicine, particularly for delivering drugs or monitoring health in humans.
Ultimately, the goal is to create a future where growing more food doesn’t come at the cost of harming the environment. With silk microneedles, it may finally be possible to boost crop yields, improve food nutrition, and protect ecosystems—all at the same time.
