About Wireless RFID Passive Sensors (Battery-Free)
Wireless RFID Sensor Demonstration Video
About Wireless RFID Sensors
Phase IV Engineering pioneered the use of wireless RFID sensors (we developed the world’s first RFID sensor integrated circuit in 1994), and we have spent more than 25 years on the cutting edge of RFID sensor design. RFID (passive) sensors are unique in that they transmit sensor data with no battery.
Types of RFID Sensors – based on radio frequency and protocol:
- Phase IV proprietary protocol for special applications – contact us for more information
Advantages and Disadvantages of Different Passive RFID Sensor Technologies
To see the advantages and disadvantages of battery-free (passive) RFID sensors compared to other wireless technologies, see the Wireless Technologies Overview Page.
UHF EPC 915/868 MHz RFID Sensor Technology
Advantages of UHF EPC 915/868 MHz
Much longer read ranges – up to 20 feet.
Large installed base of UHF EPC readers.
Sensors can be mounted on metal.
Multiple sensors can be read by one reader.
Reader radio waves tend to bounce around – allowing sensor readings that are not “in the line of sight”.
Disadvantages of UHF EPC 915/868 MHz
- Does not read through some materials as well as lower frequencies.
- Ultra-miniature sensor antennas are often not possible.
- Not allowed in some environments, such as many medical facilities.
- Frequency and protocols vary by country.
about UHF EPC 915/868 MHz RFID sensors.
High Frequency (HF) 134 KHz ISO15693 RFID Sensor Technology
Advantages of High Frequency (HF) and NFC 13.56 MHz
- HF is the standard frequency with medical products and within medical facilities.
- The short read range prevents nearby tags from accidentally being read.
- Many Android smart phones have an NFC reader – enabling the future use of RFID sensors with smart phones.
- A wide variety of readers are available.
- The lower frequency can read through many materials that UHF readers cannot penetrate.
Disadvantages of High Frequency (HF) and NFC 13.56 MHz
- Short read range of 0.25 to 2 inches.
- Typically requires a loop antenna that is at least a half inch in diameter. This prevents ultra-miniature sensors.
about High Frequency (HF) 134 KHz ISO15693 RFID sensors.
Low Frequency (LF) 134 KHz RFID Sensor Technology
Advantages of Low Frequency (LF) 134 KHz
- The electronics operate over a very wide temperature range of -55°C to 170°C.
- Very small antennas will work with the sensor – enabling extremely small sensor form factor.
- LF sensors can read through many materials such as liquids and carbon fiber very effectively.
Disadvantages of Low Frequency (LF) 134 KHz
- Typically a very short read range of a few inches.
- Large panel reader antennas are required for read ranges of 1 to 3 feet.
- RFID readers are only supplied by Phase IV Engineering. No high-volume “off the shelf” readers are available.
- Sensors other than temperature require significant engineering development work.
about Low Frequency (LF) 134 KHz RFID sensors.
Typical RFID Sensor Applications:
- Boeing 777 and 787 wheel sensors to monitor tire temperature and pressure. Learn more.
- High voltage equipment including bus bars, transmission lines, and switch gear where compact battery-free ultra-long-life sensors are the only type of sensor that will work.
- Food storage cabinets that are audited with mobile computers that have built-in RFID readers.
- Aircraft sensors including strain, temperature, fuel leak, gas tanks, and battery voltage monitoring. Sensors can be read without time-consuming removal of panels.
- Embedded sensors in rubber and carbon fiber to monitor strain, temperature, vacuum, pressure, etc.
- Long-term structural health monitoring using RFID strain sensors on structural beams, pipes, and undersea oil rig production components.
- Inexpensive moisture ingress monitoring – in road beds, bridge decks, storage containers, automobile testing.
Advantages of RFID Sensors Over Non-RFID battery-free sensors (such as SAW sensors)
- RFID readers can read many tags with one reader. This is not possible with SAW sensors.
- RFID sensors transmit both an ID# and the sensor data so the data from multiple sensors can be associated with the sensor tag. SAW sensors only transmit the sensor data, with no ID#.
- RFID sensors transmit digital data with error correction codes. SAW sensors rely on analog signals that are subject to interference that can corrupt the sensor data.
- RFID sensors can support tethered sensors and multiple sensors to the same RFID electronics. Tethered sensors allow for the sensor to monitor temperature extremes while keeping the RFID electronics away from the high temperatures. SAW sensors are limited to narrow temperature ranges and cannot utilize tethered sensors.