SAW stands for Surface Acoustic Wave technology that is used in a type of passive RFID tag that's been around since the 1970s. SAW tags use piezoelectric crystals with "reflectors" at predetermined intervals to represent a tag's data. The tags can be read from as far away as 20 meters, and can provide up to 2 foot positioning accuracy. Unlike some other tags, these can be read while mounted on metal and liquid containers. SAW tags are very small, can be read with very low power levels (<1 mWatt), and can withstand harsh environments (gamma radiation, high temperature). Oh, and they also transmit their temperature.

There were no SAW RFID tags that I saw at HIMSS 06. The biggest RFID take-away for me at HIMSS was that there is no "best" RFID system or technology; it's all about matching the application to the technology. The cool thing about the SAW tags pictured at right (from Sandia Labs) is their size and resistance to gamma radiation and high temperatures. According to the bug put in my ear by Brad Sokol, this technology is well suited to tracking surgical instruments and medical devices like consumables and implantable devices.

When imagining workflow automation through medical device connectivity, what about the autoclave as a medical device? The tracking system could track all the instruments (plus catheters, guide wires, and implantables) in a surgical suite - down to which one's are in the sterile field - ensure their sterilization, and even report their temperature. Sounds like just the thing ASP, 3M, Tuttnauer, Kimberly Clark, or Steris might want to do to differentiate or add value.

There's a new market study from IDTechEx, looking at SAW RFID tags here.

Chipless tags are digitally encoded and work at more than one
millimeter range. First- generation technologies did not meet open
standards for use by many service products. However, second-generation,
surface acoustic wave (SAW) tags are technically improved, lower in
cost, can store sufficient data, and operate at frequencies used by
conventional RFID chips. Chipless RFID can operate to more than a 10 m
range with 256 bits of data. Tags can be materials based or consist of
transistorless circuits. Transparent polymer transistor circuits are
now available from Philips, PolyIC, OrganicID, and Motorola, among

Here's a technical paper from Sandia (pdf) for you RFID rocket scientists. And for us mere mortals, this paper (pdf) from vendor RFSAW, provides a nice general introduction to SAW-based tags.