THE iButton family consists of over 20 different products, including devices that contain memory, temperature sensors, data loggers and even Java computers. Every iButton produced (to date over 100 million) has a unique silicon serial number. This feature makes the iButton ideal for use in automatic identification systems.

An assembled PICAXE iButton reader board, complete with iButton probe & piezo sounder. Although not visible here, the probe has an LED in its centre for visibility at night.

In fact, the simplest member of the family, the DS1990A Serial Number iButton, is designed specifically for identification tasks. Like all devices, its 64-bit serial number is guaranteed to be unique and therefore traceable. iButton serial numbers are also laser engraved on the outsides of the cans so that human eyes can read them!

Owing to the small size and robust nature of the iButton package, it can travel with a person or object to provide many useful functions, including access control, environmental monitoring and data storage.

The stainless steel button is durable enough to be worn everyday on an accessory like a ring, key fob, wallet, watch, metal card or badge. It is also water resistant and so can be worn while washing or swimming.