OXEMS unique RF-Barcode™ Technology
The enabling technology of the OXEMS System is based upon original research carried out at the department of Engineering Science at the University of Oxford. The research was based around the idea of evolving traditional RFID technology for use in this application.
Traditional RFID technology uses an externally provided electromagnetic signal from an energising device to excite a simple resonator within the RFID tag. The resonator in turn powers circuitry to enable a sensing device to interrogate data stored in the RFID tag. There are, however, two significant challenges with this approach when applied to subsurface assets:
- The frequencies used for RFID devices are typically in the range from several 10s of MHz upwards. These frequencies are fine for RFID tags that operate in the air over relatively short distances (for example, product identifiers in shops and some travel cards) but putting them anywhere near water limits their capability and, at the depths of buried assets (typically down to two meters), can completely prevent their recognition by a sensing device.
- The use of data storage in an RFID tag limits the longevity of the tag to the length of time data can be guaranteed to be stored correctly in a silicon device – currently around 10 to 15 years. This is too short to mark assets with a minimum design life of 50+ years.
To overcome these issues, the original OXEMS research at the University of Oxford led to the development of tags that differ in two important ways:
- They operate in the KHz range, making them visible at depth and in underwater conditions
- All additional circuitry (including all silicon) is removed to overcome the longevity issue. OXEMS Tags have been independently assessed as having an operational life of more than 100 years, even in underwater conditions at depths up to 2 metres.
The resulting resonator was then enhanced to resonate at more than one frequency, resulting in what is, in effect, a factory-set barcode. By using different frequency combinations OXEMS Tags can be used to indicate specific subsurface assets: for example, valves on water pipes, T’s on water pipes, joints on gas pipes, and so on. This is OXEMS RF-Barcode™ technology.
The longevity of OXEMS Tags is crucial, so a further issue for devices of this type is that they must also prevent any moisture ingress. Moisture reduces the signal strength (making the device harder to detect) and changes the frequencies (causing incorrect readings). OXEMS has solved this problem.