Kittenman writes: The BBC is carrying information on a type of contraception (funded in part by Bill Gates) that takes the form of a microchip, inserted under the skin. The chip releases contraceptive hormones to the body until wirelessly advised not to do so. This device has several interesting applications and issues associated with it. The researchers are already working on making the device secure against unauthorized transmissions. There's also the issue of making it easier for governments to control population levels. The chip will be available from 2018. This correspondent will watch the issues with interest.