A 'testicle bath' which zaps sperm with ultrasound waves could revolutionise male contraception, its designers hope.
Men would place their testicles in the small bowl-like device, which emits ultrasound waves that limiting sperm production and mobility for up to two months.
It was designed by Rebecca Weiss, who wanted to create male contraception after she contracted cervical precancer, which she linked to the HPV virus and taking hormonal contraceptive pills.
She said the device, called COSO, is painless and reversible and should prevent unwanted pregnancies.
But so far, ultrasound has only been trialled as a contraceptive on animals and the COSO device has not been tested.
Condoms and a vasectomy are currently the only two contraceptives targeted at men, while there are 12 tailored to women.
The proposed COSO device needs to be filled up with water, which it automatically heats to the temperature of a warm bath. A man then sits with his legs spread apart and puts his testicles in the water, which are ultra-sounded for two 15-minute treatments, two days apart
If the device receives the go-ahead, it would include an app that can be shared with a partner, keeps track of treatments and reminds men when to use the gadget again
Ultrasound - currently used to reduce pain and speed up healing for deep tissue injuries - was first proposed as a contraceptive in the 1970s and is thought to work by generating a deep heat in the testicular tissue.
This alters sperm mobility, which prevents the female egg from being fertilised and temporarily suppresses the creation of new sperm.
