||[Nov. 24th, 2004|09:33 am]
VeriChip TXI400L |
12mm human-implantable RF/ID tag
Most people are familiar with laser scanners at supermarkets that scan bar codes and identify
goods to be purchased. Bar codes are used by the postal service to automatically identify packages and letters. VeriChip's electronic identification system provides essentially the same capability for the identification of people, where an ID system using labels is not practical.
There are two basic differences between electronic identification and bar code technology: how the ID number is read and how it is stored. Electronic identification uses a common low-power radio signal to read an ID number stored in a tiny electronic circuit rather than laser light to read a label. Electronic ID based on these radio signals is also referred to as radio frequency identification, or RFID. These low-frequency radio waves, unlike light, can penetrate all solid objects except those made of metal. Therefore, use of electronic ID allows the number to be stored inside the person, where it is permanent and is not subject to being lost or altered, out of view, or becoming worn and unreadable as an external bracelet, for example, would be.
The tiny electronic device used to store the electronic ID number is called a transponder. VeriChip's transponder is about the size of an uncooked grain of rice. The transponder is easily inserted, similar to starting an intravenous line. The device then remains within the person, where it provides a unique ID number any time it is scanned by a compatible electronic ID reading system.
VeriChip reading systems, or scanners, send a signal using a frequency of 125 kHz, much lower than the frequencies used in AM medium-wave broadcasting. The power of the radio signal sent by the scanner is less than one one-thousandth of a watt (one milliwatt), which is far less than the power transmitted by a child's two-way radio (walkie-talkie). VeriChip scanners are approved by the FCC in the US. and by similar organizations in other countries (PTT's) to operate as low-power radio- frequency devices not requiring licensing.
VeriChip's transponders are passive devices, meaning that the transponder carries no battery and remains inactive most of the time. The transponder's tiny electronic circuit is energized by the low-power radio beam sent by a compatible reading device. The transponder sends the ID number as a radio signal back to the scanner, which then decodes the number and displays it on a small screen similar to that on an electronic calculator. Since the transponder contains no battery there is nothing to wear out.
The transponders are cylindrical, measuring 11 mm in length and 2.1 mm in diameter. There are only three components inside: a
computer microchip (custom integrated circuit) that is shown in the figure on a human finger. This microchip contains the unique ID number assigned to the transponder, and all of the electronic circuitry necessary to send the number to the scanner when it receives the scanner radio signal.
The second component of the transponder is a coil of copper wire wound around a ferrite (iron) core. This functions as a tiny radio antenna to pick up the signal from the scanner, and to send the encoded ID number from the microchip back to the scanner. The third component is a capacitor used for tuning. The internal structure of the transponder is shown above.
Each transponder's unique ID number is encoded into it during the manufacturing process. A laser etches this code onto the surface of the microchip prior to transponder assembly and encapsulation in glass. Once the number is encoded it is impossible to after. Encoding of the number itself uses 38 bits of information which allows 490 billion possible ID numbers.
The outside of the transponder is a soda lime glass that has been specially selected for known biocompatibility. During manufacture, this glass is hermetically sealed so it is not possible for any moisture from the host human's body fluids to reach the electronics inside.
While glass is bio-chemically inert it is also very smooth, which, in rare instances could allow the transponder to move around in the body once injected.
Therefore, we have devised a special, porous polypropylene sheathe that covers one end of the transponder. This Biobond® coating offers a surface with which fibrous connective tissue begins to bond within 24 hours of the injection.
The site of the insertion may be the shoulder or, for identification of a medical device implant, near the implant. For these insertions, each transponder comes pre-loaded inside a needle cannula, and this assembly is packaged in a pre- sterilized plastic envelope. Each introducer set is discarded after one-time use.
Numerous studies have been performed to demonstrate the safety of the transponder. These studies have involved mammals, birds, fish, and reptiles that have shown no adverse reactions to the transponder, either biological or behavioral