A German inventor's 'testicle bath' birth control device for men has won the top prize at the country's James Dyson Awards.



Rebecca Weiss was honoured for her COSO birth control device and claimed the award that "celebrates, encourages and inspires the designers of new problem-solving ideas".

The invention uses an ultrasound "testicle bath" to temporarily halt sperm mobility. It only needs to be used every few months to keep sperm inert and prevent eggs from being fertilised during sex.

Weiss said the inspiration for the device came after she was diagnosed with cervical cancer.

She told Dyson Award officials: "When my partner and I were looking for an alternative method, we became aware of the lack of male contraceptives.

"This problem is not unique to me personally. It affects many others as well as is made evident in the current growing public discussion about the lack of contraceptive alternatives."