Microchip Markets RFID Technology that Transmits via the Human Body

By Claire Swedberg

The company says its BodyCom active tags and readers are more secure than RFID technology that transmits signals through the air, making it suitable for controlling access to cars, buildings, power tools, computers and firearms.

Several companies are currently beta-testing a radio frequency identification system from Microchip Technology that uses the human body as a conduit for transmissions between an interrogator and a tag. Microchip's platform, known as BodyCom, can be utilized to control access to a building, or to control the usage of a device, such as a computer or a weapon. The companies, located in various parts of the world, are testing ways in which to integrate the technology into their own solutions, such as keyless vehicle-entry systems.

While traditional RFID systems transmit data through the air, simply requiring a tag or a receiving unit to come within transmission range of an interrogator, the BodyCom solution requires that both tag and interrogator be within close proximity to a person's body. By leveraging the body to transmit a signal, BodyCom does not need as much power, nor does it require a conventional RFID reader antenna, according to Edward Dias, the embedded-security business-development manager of Microchip's MCU8 (8-bit microcontroller) division. This would mean the battery life of a device such as a remote control or an ID tag would be longer, he explains, and that the transmission itself would be more secure, since there would be no over-the-air RF signals that could be intercepted.

The BodyCom development kit, available from Microchip for $149, includes a base unit and two battery-powered RFID tags.

The system's base unit (reader) employs a capacitive coupling pad instead of a conventional reader antenna to transmit a 125 kHz signal (or "challenge") via the human body—which acts as a secure communication channel—to a tag (or "mobile unit"). The mobile unit then responds by transmitting an 8 MHz signal, encoded with that tag's unique ID number. The tag's transmission also travels along the body and back to the base unit, which responds by triggering an action, such as unlocking the door of a car or building.

For approximately 15 years, Microchip has provided wireless technology used in such devices as garage door openers and keyless-entry car locks consisting of a radio receiver and a transmitter. However, Dias says, those systems typically communicate via a low-frequency (LF) inductive field, resulting in an over-the-air signal that car thieves or other individuals can tamper with. There are devices available on the market that can, for example, capture transmissions from a car lock over the air, and relay that signal farther away to a vehicle owner's remote controller, thereby tricking the system into thinking the remote is within close proximity to the door lock.

Consequently, in order to combat that security concern, traditional RFID systems may require a user to enter a password or provide some other manual action to prompt a response, such as unlocking a door. Using human conductivity makes such protective measures unnecessary, Dias says, since the transmission is secure.

According to Dias, the BodyCom base station is designed to respond to touch in order to commence communication. When the base station detects that someone is touching its capacitive coupling pad—which resembles a printed circuit board antenna—it sends a low-power transmission, using the body's exterior as a capacitive coupler. The battery-powered mobile unit in the user's pocket or hand has an antenna that picks up this 125 kHz transmission (the system can be set either so that the tag must be in contact with a person, or so that it can be positioned several inches from a user's skin and still send and receive data), and responds by transmitting an 8 MHz signal encoded with its own unique identifier. The tag's signal travels along the exterior of the user's body until being received by the base station.

In the case of a vehicle's keyless-entry system, the base unit's capacitive coupling pad could be attached to the car's door handle or bumper, and the user carrying a BodyCom tag in his or her hand or pocket would simply touch the pad. This contact would prompt the mobile unit to communicate with the tag and trigger the lock to release, allowing that person to enter his or her car and start the ignition.

Microchip Technology's Edward Dias

The system could also be used to identify an individual before that person operates a piece of equipment. In the case of a computer, a BodyCom base station, including its capacitive coupling pad, would be integrated within the computer, which would fail to operate until the base station received transmission from an approved mobile unit. The same setup could be used for power tools or firearms, rendering them inoperable to all but those with the approved mobile unit on their person. In such applications, the base unit's capacitive coupling pad could be built into the handle of a tool or weapon, for instance.

The technology could also be used with gaming consoles, identifying an individual and linking him or her to that person's gaming history if he or she, for example, visited a friend possessing the same gaming system.

Additionally, the solution could be deployed to control access to a home's pet door. In such a scenario, a BodyCom base station's capacitive coupling pad would be installed at the pet door's entranceway. If a dog or cat wore a BodyCom tag (which could be designed to be as small as a quarter) on its collar, the animal would simply need to come within 4 or 5 inches of the capacitive coupling pad, or touch it directly, in order to prompt the system to unlock and allow that animal entrance. In the meantime, users could be assured that other pets or wild animals would not be able to enter the house through that same door.

Although conventional radio frequency identification could be used to accomplish many of the same functions, Dias notes, RFID transmissions traveling through the air would not be as secure, since they could theoretically be intercepted by an unauthorized user equipped with the appropriate RFID reader. What's more, he says, the solution is simpler to implement since the technology does not require antennas, as a standard RFID system would. Conventional RFID, he adds, would require greater power to create inductive fields when transmitting a signal.

The reason why BodyCom base unit employs 125 kHz to transmit a signal to the tag is that this particular frequency is the one most typically used for other keyless-entry technologies. The base unit can be powered externally or be connected to a battery to power that transmission. The mobile unit, powered by a small replaceable cell battery, can remain dormant until receiving a 125 kHz signal from the base station, at which time it would transmit an 8 MHz signal.

The BodyCom technology has been in development for about a year, Dias says, and is now being tested by companies that he declines to name or describe. The most common use cases, he indicates, are initially in access control.

"The technology can be configurable by the user," Dias states. "You could have proximity on both sides," in which case, a user's hand would only need to come within a few inches of the base station, while the mobile unit could be close enough to the user when stored in a purse or a briefcase to still utilize the human body to complete the transmission. Alternatively, the system could be configured so that both the base station and the mobile unit must be in direct contact with a user's body.

Dias says the company receives calls daily from businesses with new ideas for how the technology could be implemented. For example, some firms are considering employing the technology for easy access control by installing a base station in a floor pad that users would walk over. The base unit's transmission could travel through a person's shoe and over that individual's body to the mobile unit in the user's pocket, or around his or her neck on a lanyard, thereby triggering the door to open so that the person would not need to touch anything to prompt the door to open. Moreover, the system could operate in a motorcycle helmet, requiring contact between a mobile unit in the helmet and the individual's head in order to trigger the bike's ignition to activate.

Microchip Technology is offering a BodyCom development kit for $149, including a single base unit and two mobile units with the necessary firmware to operate. "When you introduce this kind of technology to a room full of engineers," Dias says, "you can see the wheels start spinning" as they generate more ways in which it could be used.