Watch out for those Tattoos says Apple

Apple has warned customers with tattoos around their wrists, they may experience performance issues when using its newly released Watch due to the ink blocking its sensors.

The manufacturer has received a number of complaints surrounding the heart rate sensor on the device, since it went on sale in April.

Apple confirmed in a statement there are numerous factors which can affect the Watch's ability to detect a heart beat, including temperature, motion and changes to skin colour - such as tattoos.

The heart rate sensor on the smart watch uses technology known as 'photoplethysmography' to detect the amount of blood flowing through a users wrist by reflecting light off the skin.  Apple said;  "Permanent or temporary changes to your skin, such as some tattoos, can also impact heart rate sensor performance.  "The ink, pattern, and saturation of some tattoos can block light from the sensor, making it difficult to get reliable readings".