International scientists led by a man called Dr Wang are working on a new male contraceptive.

The research team drew inspiration from cocktails, which bartenders often make by layering colourful liquids in a glass.

If the beverage is stirred or heated, the layers combine into a uniform liquid.

Dr Wang and colleagues wondered if they could use a similar approach to inject layers of materials to block the vas deferens, the duct that conveys sperm from the testicle to the urethra.

Applying heat would cause the layers to mix, breaking them down and “unplugging the pipeline”.

Their ideas have been tested in male rats. The team sequentially injected four layers of materials into the vas deferens to create a hydrogel that forms a physical barrier to sperm.

It contains gold nanoparticles, which heat up when irradiated with near-infrared light; ethylenediaminetetraacetic acid (EDTA), a chemical that breaks down the hydrogel and also kills sperm; and finally, another layer of gold nanoparticles.

The injected materials kept the rats from impregnating females for more than 2 months.

However, when the researchers shone a near-infrared lamp on the rats for a few minutes, the layers mixed and dissolved, allowing the animals to produce offspring.

The researchers say that while this pilot experiment is promising, more research is needed to verify the safety of the materials.

The full report is accessible here.