Biofertilisers depend on beneficial bacteria and fungi reaching the plant, yet applying them to soil leaves that outcome at the mercy of soil chemistry, moisture and competing microbial communities. Researchers in the NUS Department of Biomedical Engineering have taken the delivery problem out of the soil altogether, using dissolving microneedle patches that introduce living biofertiliser directly into plant leaves or stems.
The patches are made from polyvinyl alcohol, a biodegradable polymer, and dissolve within about a minute of being pressed into plant tissue. In greenhouse tests on choy sum and kale, treated plants grew faster by shoot biomass, leaf area and height while using over 15 per cent less biofertiliser than standard soil inoculation. Dosing becomes controllable in a way that broadcast soil application never allows.
The researchers also tracked where the microorganisms went. Bacteria introduced through leaves were observed moving to the roots, where they supported a more beneficial root microbiome, and the method was successfully applied to a beneficial fungal strain as well. The study was published in Advanced Functional Materials, and the lead group holds appointments in the College of Design and Engineering and the Institute for Health Innovation and Technology.
Early applications are most plausible in urban and vertical farms and for high-value crops, settings where labour per plant is already high and precision is valued. Scaling to field agriculture would require automation, and the team points to robotic application as the next engineering question. The underlying idea, borrowing transdermal drug delivery for plants, is a neat instance of technique transfer between biomedical and agricultural engineering.