Microneedles Could Boost Plant Growth and Reduce Fertilizer Waste

Microneedles may promote plant growth and reduce fertilizer waste.

Microneedles Could Boost Plant Growth and Reduce Fertilizer Waste

Researchers at the National University of Singapore (NUS) have developed a "magic tool"—microneedles—to reduce farmers' fertilizer spending and increase production, according to New Atlas. 

In their paper, published in the journal Advanced Functional Materials and titled "Delivering Biofertilizers Using Microneedles Improves Plant Growth Through Microbiome Engineering," Professor Andy Tai and his colleagues explored the two main sources of inspiration for their innovation: microbes found in the human body and the injections used to treat patients.

Inspiration

"We were inspired by the ability of microbes to migrate within the human body," said Tai, who led the research as the principal investigator at NUS's iHealthtech Institute of Innovation and Health Technology. 

"We hypothesized that by delivering beneficial microbes directly to plant tissues, such as leaves or stems, they could reach the roots and perform their function more efficiently and with less susceptibility to soil conditions."

To deliver these beneficial microbes—which act as a biofertilizer—directly to where the plants need them, Tai’s team developed patches of soluble microneedles. 

Using a combination of PGPR (promoting plant root bacteria) from Streptomyces and Agromyces-Bacillus species to enhance nutrient metabolism and stimulate plant growth hormones, greenhouse-grown cabbage and Chinese vegetables grew faster in terms of height, leaf surface area, and stem mass.

This increased growth was accompanied by significant savings, with biofertilizers being used at a rate of 15% lower. This improvement is attributed to the precise delivery of the fertilizer, which reduces waste and, consequently, minimizes the damage caused by fertilizers reaching unintended locations.

Tiny Patches on a Row of Needles

Using polyvinyl alcohol (PVA), an inexpensive and biodegradable polymer, the team created patches (1 cm²) containing a short row of microneedles—140 µm for leaves or 430 µm for stems—within a 40 x 40 array of 140 µm-long pyramids.

The researchers then mixed microbes into a PVA solution, which they poured into microscopic molds before attaching the microbes to the needle tips. By simply pressing this “reverse cap” with their thumb, or using a hand applicator to distribute the force evenly, the needles remain inside the plants undamaged and dissolve after about 60 seconds, leaving the microbes behind.

3D Printing

For ease of production and immediate use, the needle patches can be 3D printed. Even when applied to large leaves, they provide uniform insertion. Thanks to the patch design, the microbes remain viable during storage for up to four weeks, allowing for long-term storage.

Unlike biofertilizers added to the soil, there is virtually no waste or spoilage, meaning that crops—including valuable ones—receive their full medicinal benefits. Tai and his team hope that microneedling technology will become a staple in vertical and urban food and pharmaceutical farms in the near future.

"Our main focus is on scalability," he added, explaining his intention to explore integrating microneedling with agricultural robots and automated systems to make it applicable on large farms. The technology will also be tested on a wider range of crops, such as strawberries, to investigate how efficiently these microbes can be transferred from the leaves to the roots.