PHOTO: Amal Graafstra

An X-ray shows Amal Graafstra's hands with implanted RFID tags.

When I open my front door, I don't reach for a key. When I log into my computer, I don't touch my keyboard. When I start my motorcycle, again, no key needed. Instead, I just wave my hand and I'm in business.

I was one of the first do-it-yourselfers to have a radio-frequency identification (RFID) tag implanted under my skin. In fact, I have two—one between the thumb and index finger in my left hand, the other in the matching spot on my right hand.

So what's a nice guy like me doing with a microchip in each of my hands? My life as an RFID guinea pig started in early 2005. At the time I was managing servers for medical facilities around Seattle, a job for which I carried around a ring of keys to almost 100 different doors and drawers.

That bulky key ring got me thinking. It struck me that modern keys are just crude identification devices, little changed in centuries. Even if each lock were unique—most aren't—keys can be copied in any hardware store and, once distributed, are hard to control.

I considered biometric authorization, in which access is granted only if a scanned physiological trait, such as a fingerprint or the pattern of an iris, matches a pattern stored in a database. But I found biometrics to be neither cheap nor reliable, so I turned my attention to RFID—specifically, the access card systems commonly found in office buildings.

Two weeks later, I was sitting in a doctor's office. After sterilizing the tiny glass cylinder, the doctor injected a small amount of local anesthetic to numb my left hand. She made a 2-millimeter incision in the fleshy part next to my thumb, lifted the skin, and slipped the tag inside. She applied some skin glue and bandaged it up. Just like that, I became one of the few people on Earth walking around with a radio transponder in my hand.

In an RFID “lock ” system, each RFID tag, which is essentially a minitransmitter, sends out a sequence of radio-frequency pulses representing a unique number, usually 10 to 16 digits in length. An RFID tag's memory typically ranges from a few bits to 128 bits, in the common ISO-compliant tag, to several megabytes. The locks are programmed with a list of authorized numbers; if your tag emits one of those numbers, you're in. If not, you're not. If someone loses a tag, no problem: that serial number can be removed from the list.

Now, if the tag is implanted in your body, I reasoned, so much the better: it's impossible not to have it when you need it. The RFID tag that makes sense for implantation is embedded in glass and is about the size of a grain of rice. It consists of a microchip and a metal coil, which acts as an antenna. Known as a passive tag, it is an inductive system—that is, a voltage is induced when the coil is in the magnetic field of an RFID reader. Because it's battery-free, a passive tag requires no maintenance.

Human implantation of RFID tags dates back to at least 1998, when Kevin Warwick, a professor of cybernetics at the University of Reading, in England, implanted an RFID tag above his left elbow, which he used to control doors, lights, and computers around his office. In 2004, VeriChip Corp., in Delray Beach, Fla., had a chip approved for implantation in people. Since then, according to the company, approximately 220 people in the United States (more than 2000 worldwide) have willingly had VeriChip tags implanted into their upper arms. Typically, the implant is used to alert doctors to medical conditions, such as diabetes, if a person is admitted to a hospital unconscious. By scanning the tag, doctors can identify a patient and access personal medical information. There are more frivolous uses, too: some nightclubs have used them to let patrons enter VIP rooms and bill drinks directly to their accounts.

For my purposes, VeriChip tags had a number of drawbacks. The company requires doctors to register each implantee in a special database. Their tags have a special coating that flesh grows into, locking the tag in place and making its removal difficult and painful. The equipment for reading the tags, priced at around US $600, is difficult to hack. Additionally, according to approval requirements set up by the U.S. Food and Drug Administration, VeriChip's tags must be implanted in the upper arm, which is awkward to use with door access and other systems—it's a lot easier to open your door or unlock your car by waving your hand rather than by wiggling your bicep.

VeriChip seemed like an awkward option, so I considered animal tags, or “pet chips, ” which have been around since the late 1980s and which I hoped might be more flexible. Currently, Avid Identification Systems, one of the pioneers in implantable tags, has 19 million to 20 million implanted animals—not including livestock—in its database. Unlike a collar tag, a pet chip is impossible to lose and hard to remove, and it is far less painful for the pet to receive than an ear tattoo.