Empa develops liquid-core fiber for insecticide-treated mosquito nets after three years of tuning
Empa's polymer fiber with a liquid insecticide core releases the agent through its sheath and suits compounds that evaporate when heated. Large-scale tests are still needed.
Researchers at Empa in St. Gallen, led by Edith Perret of the Advanced Fibers laboratory, have developed a liquid-core fiber for insecticide-treated mosquito nets, according to newswise.com. newswise.com
newswise.comnewswise.comOpen source ↗ The work took three years of development and testing within the Innosuisse project MalCoFil. The fiber consists of a polymer sheath and a liquid core made of a carrier fluid that contains the insecticide.
Why current nets reach their limits
According to the WHO, more than 280 million people in 80 countries contracted malaria in 2024. More and more mosquitoes are developing resistance to the pyrethroid insecticides commonly used for protection. Preventive medications and a vaccine exist, but their effectiveness is waning, and for most people in the affected countries they are unaffordable. Repellents and mosquito nets therefore remain the primary means of protection.
Until now, treated nets were either impregnated with pyrethroids or made from synthetic yarns containing a mixture of polymers and insecticides. Such yarns are produced by melt spinning, in which molten polymers are pressed through fine nozzles at high temperatures. Many non-pyrethroid insecticides evaporate when heated, which limits this approach.
How the liquid-core fiber works
The insecticide gradually diffuses through the polymer sheath to the fiber surface, while the carrier fluid stays inside. newswise.com
newswise.comnewswise.comOpen source ↗ According to Perret, this allows novel insecticides that would evaporate at high temperatures to be used, and the fiber can be loaded with larger amounts of insecticide. She estimates that the effect lasts about three years, including multiple wash cycles, but this still has to be confirmed in large-scale testing.
The mechanical properties of the fibers are preserved with the new technology. The yarn must be suitable for weaving, have high tensile strength and not become brittle. To achieve this, the team balanced a polymer for the sheath that is permeable but not overly so, and a carrier fluid for the core to which various insecticides can be added.
Two Swiss industry partners took part. Vestergaard Sárl, which makes insecticide-treated nets, has tested the mechanical properties of the new yarns during knitting and their effectiveness in killing mosquitoes, including resistant species. Monosuisse AG, which makes high-performance filaments, worked with Empa on a new spinning nozzle that can be scaled up for industrial production. Whether the fibers can be transferred to industrial production and distributed on a larger scale remains to be seen.
