Glass capsule / injectable transponder
Animal identification
What is it?
A glass capsule transponder is a tiny RFID chip and coil antenna sealed inside a biocompatible glass tube, typically 12 × 2 mm. It is injected under the skin of an animal using a hypodermic needle. Once injected, it remains in place for the animal's lifetime. This is the technology behind pet microchipping – most dogs and cats in developed countries have one. It is also used in horses, zoo animals, and laboratory animals.
How it works
The transponder is a ferrite-core coil antenna wrapped around an LF chip, sealed in borosilicate glass coated with Parylene C (a biocompatible polymer that promotes tissue encapsulation). It is loaded into a sterile single-use implant needle (typically 12 gauge) and injected subcutaneously, usually between the shoulder blades. Within days, tissue grows around the glass capsule, anchoring it in place. The tag is read by holding an LF reader close to the implant site.
Use cases
- Pet identification (dogs, cats)
- Horse identification and passport compliance
- Zoo and wildlife management
- Laboratory animal tracking
- Exotic pet identification
- Racing animal identification (greyhounds, pigeons)
Pros
- Permanent – lasts the lifetime of the animal
- Cannot be lost, removed, or transferred
- Biocompatible – does not cause adverse reactions
- Standardised globally (ISO 11784/11785)
- Extremely small and unobtrusive
Cons
- Requires a trained person to implant
- Very short read range (10–15 cm)
- Read-only – data cannot be updated after implant
- Small risk of migration within the body
- LF only – no long-range or group reading
Specifications
| Power type | Passive – powered by reader signal |
|---|---|
| Frequency | LF (134.2 kHz, ISO 11784/11785) |
| Read range | Up to 15 cm |
| Lifespan | Lifetime of the animal (20+ years) |
| Price range | $2–$10 per unit (plus implantation cost) |
| Environmental rating | Biocompatible; sealed for lifetime subcutaneous use |