Radio-frequency identification

RFID systems consist of three components: a tag (transponder), a reader (interrogator), and a host computer. The reader emits radio-frequency signals that power and communicate with the tag. Passive tags harvest energy from the reader's signal, while active tags have their own battery and can transmit over longer ranges. Semi-passive tags use a battery to power the chip but rely on the reader for communication.

Data is stored on the tag's microchip, typically a unique identifier (EPC or TID) and optional user memory. The reader decodes the signal and sends it to the host system. RFID operates in several frequency bands: low frequency (125–134 kHz), high frequency (13.56 MHz), ultra-high frequency (860–960 MHz), and microwave (2.45 GHz). Each band offers trade-offs between read range, data transfer rate, and resistance to interference from liquids and metals.

RFID is widely used in retail and supply chain management to track inventory, reduce shrinkage, and enable automated checkout. Major retailers like Walmart and Zara have mandated RFID tagging from suppliers, leading to significant adoption. In logistics, RFID tags on pallets and containers improve visibility and reduce manual scanning errors.

Beyond retail, RFID is integral to contactless payment cards (e.g., Visa payWave, Mastercard Contactless), electronic toll collection (e.g., E-ZPass), and access control systems for buildings and events. In healthcare, RFID tracks surgical instruments, medication administration, and patient identification, reducing errors and improving safety. Livestock and pet identification use low-frequency tags, while libraries use RFID for self-checkout and inventory management.¹

The concept of RFID dates back to the 1940s with the development of radar-based identification systems, notably the IFF (Identification Friend or Foe) used in World War II. In 1973, Mario Cardullo filed a patent for a passive radio transponder with memory, often considered the first true RFID tag. The 1980s saw commercial applications in toll collection and animal tracking.

Standardization is crucial for interoperability. The International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) have published standards such as ISO/IEC 14443 for proximity cards (used in contactless payments) and ISO/IEC 18000 for item management. The EPCglobal Gen2 standard (ISO/IEC 18000-63) is the dominant UHF protocol for supply chain use, enabling global interoperability.²

RFID has surprising niche applications. In sports, marathon runners wear RFID tags to record split times, and some footballs used in major leagues contain RFID chips to track ball movement for analytics. In aviation, RFID tags are embedded in aircraft parts to streamline maintenance and comply with safety regulations.

One overlooked area is RFID in art and museums: some institutions embed tags in artworks to monitor environmental conditions and detect unauthorized movement. RFID is also used in casinos to track chips and detect counterfeiting. A notable edge case is the use of RFID in human implants, such as the VeriChip, which was marketed for medical records but raised privacy concerns. Additionally, RFID can be used for 'chipping' of employees in some companies, like the Swedish epicenter office, which sparked debates about privacy and bodily autonomy.³

Passive tag

An RFID tag that has no internal power source and draws energy from the reader's signal.

Active tag

An RFID tag with its own battery, allowing longer read ranges and autonomous transmission.

EPC

Electronic Product Code, a universal identifier for objects in supply chains.

UHF

Ultra-high frequency, a band (860–960 MHz) used for long-range RFID.