Testicle bath contraception device wins James Dyson design award

A new form of male contraception involving tea-bagging in a testicle bath has won the James Dyson award for innovative design.

The fan-testicle device named COSO is described as an “ultrasound-based, reversible and hormone-free male contraceptive device for home use”.

The device is filled with warm water, then the testicles are placed inside as ultrasounds are emitted over several minutes. This process suppresses spermatogenesis.


The sleek and compact device combines ultrasound and temperate methods to give the user temporary infertility. It must first be administered by a doctor, then it can be used in the comfort of your own home every few months. Treatments last up to six months.

Design graduate Rebecca Weiss is credited with developing the technology that won her the top prize.

“About a year ago I was diagnosed with cancer precursor cervix due to contraception with the pill,” Weiss revealed at the Dyson awards. “After that, hormonal contraception was no longer an option. When my partner and I were looking for an alternative method, we became aware of the lack of male contraceptives.”

“So I decided to deal with the development of a new contraceptive approach for men in my master thesis in Industrial Design at the Technical University in Munich.”

Weiss worked with young men to workshop the new technology, consulting about what they would want from the device and the ergonomics of the COSO.

The next step in developing the technology will be to raise funding for clinical trials. Recent studies have shown that using ultrasound technology for contraception may be viable, but the barrier to its development is encouraging men to attend contraception appointments with their doctor.

After winning the James Dyson award in Germany, Weiss will use her testicle technology to compete against other countries’ winners on the international stage, judged by James Dyson himself.