Self-Powered Sensing Technology in Industrial IoT: UHF RFID Shows the Way

Article By : Frédéric Maricourt

Industry 4.0 developers are looking to enable battery-less solutions. That’s where UHF RFID technologies like the approach embraced by the RAIN RFID Alliance come into play.

The combined consumer and industrial IoT market is expected to reach US$11.1 trillion by 2025, according to a 2020 report by researchers at Prudour. The dramatic expansion of IoT applications is already raising some issues related to the batteries that power IoT devices — not only in terms of sustainability and environmental protection but also from a predictivity and cost perspective. Industry 4.0 developers are therefore looking to enable battery-less solutions. That’s where UHF RFID technologies like the approach embraced by the RAIN RFID Alliance come into play.

RAIN is both an industry alliance, much like the Bluetooth SIG and Wi-Fi Alliance, and a technology. As described on the alliance’s website, the acronym RAIN (for RAdio-frequency IdentificatioN) “is intended as a nod to the link between UHF RFID and the cloud, where RFID-based data can be stored, managed and shared via the Internet. A RAIN RFID solution uses a reader to read and write a tagged item, manage the data, and take action.” Membership in the alliance is open to any organization that has an interest in passive UHF RFID.

Today’s manufacturing systems use the data stored in RFID tags to enable more flexible and efficient customized products. The application of RFID technology on the factory floor has led to much higher levels of automation and standardization and has widely contributed to the ”Lean” processes of the modern supply chain. Compared with established identification technologies such as active tags and bar codes, passive RFID tags don’t need their own power supply and do not require a line of sight to operate.

Because it is an emerging technology, very few stakeholders today are able to offer solutions that turn passive RFID chips into the smart sensing devices required for RAIN RFID. Those IC families can measure parameters such as temperature, humidity, motion, ambient light, electrical continuity, and material malleability completely passively, without requiring additional components, and can transmit the acquired data to a conventional RAIN RFID reader over ranges of 5 to 10 meters.

No special HW/SW required

The data transfer from the chip to the reader takes only a few milliseconds and is completely compliant with the current EPC Gen2 protocol. The advantage for the user is that no special hardware or software is required to acquire and process measured values. Readers currently available on the market can capture and interpret the data from the chip and forward it to higher-level systems. When integrating tags based on the chip into a logistics application, for example, the asset ID and EPC number can be captured together with the sensor data.

Inlays are convertible into numerous transponder formats, from flexible labels to hard tags. A classical package version such as QFN with integrated sensor IC is suitable for use even in harsh environments.

Comparison of communication technologies
Comparison of communication technologies used for Industry 4.0 (Source: Asygn)

Predictive Maintenance Applications

The global market for battery-free RFID sensors is expected to expand at a compound annual growth rate of 13.3% to reach US$2,099 million in 2030, thanks to advancements in battery-free technology as well as a greater emphasis on research and development activities, according to Prudour.

Sensor ICs are already being used in many industrial cases — for example, in detecting pipe distortion — in which traditional sensor solutions based on strain gauges were previously required or for which there was simply no suitable solution.

Typically, a standard strain gauge requires signal-conditioning circuitry, analog-to-digital converters, and communication devices to transfer or provide the data to a PC. Now, all the necessary components can be combined in one chip, and communication is possible via UHF RFID. Neither batteries nor external sensors are required.

A wide general-use case is predictive maintenance, which can anticipate wear or breakdown, enable maintenance technicians to focus on key issues, and generate huge amounts of data in order to build predictive models. Metal superstructures, such as bridges and large buildings, are excellent candidates for such technology; crews can attend to repairs before catastrophic failures occur that would incur penalties, require costly repairs, or, in the worst case, result in injuries. Embedding free-power sensors into concrete blocks at the time of their manufacture would enable real-time access to critical parameters such as temperature or humidity, allowing builders, building managers, and building users to monitor structures over time, thereby bringing peace of mind to those stakeholders.

Heavy industrial equipment makers are also keen to use the technology for applications such as detecting overheating on turbine blades in hydro- or wind-power applications. Pressure sensors can also be used on industrial gas bottles to prevent explosions or fires. Yet another emerging case is incorporating chips into elastomers, for example, to allow vehicle weight or load to be measured via pressure sensors embedded in tires.

Free-power sensors
Embedding free-power sensors into concrete would enable real-time access to critical parameters so that structures could be monitored over time. (Source: Asygn)

Beyond industrial applications, developers are targeting use cases in agriculture and health care. Drones embedded with readers can monitor temperature, humidity, and light conditions in greenhouses and open fields. Livestock fitted with ear tags can be tracked in the field, and their body temperature can be monitored to detect illness. And by incorporating RFID sensors into prosthetic devices, strain or temperature deviation can reveal malfunctions so that technicians can assist patients by repairing or replacing a defective prosthesis before it causes a problem.

Industry has already fully accepted IoT. The task now is to make Industry 4.0 solutions leaner and more efficient to maximize ROI, and battery-free UHF RFID technologies are showing the way.

This article was originally published on EE Times Europe.

Frédéric Maricourt is sales director at Asygn.


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