A dog microchip works using technology known as radio frequency identification, or RFID. It uses radio waves to transmit the dog's information from the microchip, also known as an RFID tag, to the microchip reader. The microchip uses electromagnetic forces for power to send the stored information to a device that interprets it, which means that the microchip does not require a battery or other internal power source.
The microchip is approximately the size of a grain of rice, but it holds a number of components that help it to function. It is enclosed inside a nontoxic, biocompatible glass material to prevent the dog from having an allergic reaction to the chip when it is implanted. Some chips are also surrounded by a cap that is constructed of a polypropylene polymer to prevent it from moving around inside of the dog. The silicon microchip is stored inside the capsule along with a tuning capacitor and a copper antenna coil. The capacitor sends power to the microchip, while the antenna allows the scanner to pick up the information stored on the microchip. The type of RFID tag that is used in dogs is called a passive RFID tag. This type of RFID tag can only hold information. The information stored on the tag is typically a special identification number that is assigned to the dog.