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How does a microchip scanner work?

In most cases scanning for a microchip in an animal is an easy process, but in a small minority it can be tricky due to growth of the animal, a thick coat or perhaps even migration of the microchip. Under these conditions it is especially important to understand how scanners work, the best way to use them when scanning for microchips, and their potential limitations.

Pocket or hand scanners are best used in contact with the animal, and the scanner should be passed over the animal using small concentric circles.

Dillon demionstra

coil generating a field

Each scanner possesses a coil which generates a radio signal field, the signals within this field, when passed over a microchip, power the microchip and enable it to generate it's own radio signal field which the scanner detects and decodes as the unique 15-digit microchip number. At a basic level the microchip will respond best when its field is in the same general direction as the field generated by the scanner, this will usually give the maximum range. The range of the fields produced by the scanner and the microchip can vary greatly depending on the microchip type, the type of scanner used, environmental conditions, and the orientation of the microchip in the animal in relation to the scanner when scanning. As a general rule most handheld pocket scanners have a read distance of between 3-5cm. The coil in our Universal Scanner is across the front so it should always be held paralell to the animal when scanning. Moving the scanner in small concentric circles when scanning also allows for best detection if the microchip is laying in a different position when compared to the coil in the scanner.

The 'air coil' scanners with a round flat head, such as those present in the Halo and PetScan, generate a field around the whole of the head. Although they have a greater read range when used like an axe, (see below image), this means that the scanning potential of the rest of the coil is wasted - and therefore holding scanners in this way is not recommended. We always recommend that they are held flat and close to the animal. Scanning in all circumstances should always be carried out slowly and in a methodical fashion to cover the whole animal. 


 The performance and read distance of scanners can also be affected by the following:

  • Size and type of microchip being scanned - Some microchips may have larger read distances than others. For example mini microchips have a shorter and smaller ferrite rod core, meaning that their read distance is reduced when compared to a regular sized microchip.
  • The orientation of the microchip in an animal in relation to the scanner when scanning - Microchips are best read when the scanning field produced by the scanner is paralell to the field produced by the microchip.
  • Model of scanner - Depending on the coil type and size, some scanners have a greater read range compared to others.
  • Scanning technique used by the operator - Scanning too quickly, or holding the scanner too far away from the animal when scanning.
  • Scanning near large metal items or items which produce an electromagnetic field - These items can interfere with the scanning field produced by the scanner and affect the ability of the scanner to pick up the signal sent out by the microchip. We recommend scanning away from such items, as well as removing any metal collars, harnesses or tags from an animal when scanning.
  • Using the scanner in close proximity to other microchips - If there are other microchips in the immediate vicinity, or even within the animal being scanned, then this can interfere with scanning as the scanner may pick up the signal sent out by these microchips, rather than the one that the scanner operator is trying to read.

Understanding how scanners work, as well as any possible limitations, is essential for any scanner operator. The most common reason for a microchip to be missed is due to incorrect scanning technique or a lack of understanding on how scanners work.