Passive RFID Tracks Conditions for Construction, Smart Buildings

Smartrac and SensThys have partnered to develop a moisture-, humidity- and temperature-sensing solution that is being piloted for roof leak detection and concrete curing; the technology companies are also selling a starter kit for a variety of use cases.
Published: November 11, 2019

SensThys and Smartrac Technology Group are releasing a new solution that employs SensThys’s UHF RFID readers and software algorithms with Smartrac’s moisture-, humidity- and temperature-sensing RFID inlays and tags. The partnership is intended to bring passive RFID sensing into commercial applications at an affordable price.

The solution is initially focused on the construction and smart building markets, for use in leak detection and concrete curing. Currently, SensThys is piloting the system with an unnamed company on its large, flat roof. Smartrac’s sensor tags are embedded in sections of the roof to enable the detection of water leaks, while the solution is also being tested to help determine when concrete is fully cured.

The SensX Extreme reader

The tags can be used in common building materials, such as gypsum board, insulation, roofing, flooring and concrete. SensThys is employing its own SensX Extreme reader with an array of sweeping sensors, such as an accelerometer, a gyroscope, a barometric pressure sensor, GPS technology and Bluetooth Low Energy (BLE)-based beacons. In addition to tracking sensor data, the RFID tags can aid those in the construction industry by providing location data, according to Neil Mitchell, SenThys’s VP of sales and marketing.

Smartrac launched its first such tag, the Sensor Dogbone, in February 2015. At the time, the company claims, this was the industry’s first passive RAIN RFID moisture-sensing inlay. “The product resulted from our cooperation with sensor specialist RFMicron [now Axzon],” says Bill Barr, Smartrac’s VP of global product and partner services. The inlay employs Axzon’s Magnus S2 IC and was specially designed to measure moisture conditions in industrial environments

In May 2016, Smartrac took the Sensor Temperature Dogbone to market based on the Magnus S3 IC. The tag was designed for use in cold chain management, as well as for the grocery and agriculture sectors. “In general, our sensor inlays are intended to serve multiple markets,” Barr says, such as industrial, logistics, perishables, automotive, health care, construction and smart buildings. “It’s all about improved product management and quality control. Passive sensor inlays provide great performance at a very reasonable cost level.”

Since the company’s first sensor labels were developed, Barr says, they have been qualified by several global industrial, construction and automotive companies for their production, manufacturing and logistics processes. Most of the applications for the tags to date have leveraged standard fixed readers, while some also employ handheld models. Readers require some software algorithms to capture and interpret the sensor data, along with an Electronic Product Code (EPC) number. SensThys has been developing readers, software and solutions for some of its customers, says Jo Major, the firm’s CEO, which are designed to interrogate the sensor tags relatively quickly. SensThys’s software algorithm is designed to manage the sensor data, he adds.

The two technology companies first began working on the solution after their representatives met at this year’s RFID Journal LIVE! conference, held in April in Phoenix, Ariz. Many off-the-shelf RFID readers can capture sensor data from Smartrac’s sensor tags, but the read rate is relatively slow and sensor data related to moisture readings is not able to be accurately reported. Therefore, Smartrac had been looking for faster RFID reading systems for the sensor technology. “SensThys has extremely good technical knowledge of RFID reading and integration,” Barr states. “Together with SensThys, we can serve large industrial end users, especially in the NORAM [North America] area.”

In the case of smart buildings, the sensor tags can be used with SensThys readers to create smart building materials. In a household, for instance, tags installed in bathrooms can identify a potential leak near a toilet, bathtub or sink. SensThys has also developed a rolling reader cart with a SensX Extreme (IP67-rated) reader, Mitchell says, which can read tags installed in rooftops and at other locations. During the rooftop pilot, for instance, the cart can be placed on the roof and then be pushed up and down the flat roof area, where it reads tags embedded in the roofing material.

For the pilot, Mitchell explains, the tags were already embedded in the material. (In the future, the technology companies predict that manufacturers of building materials will embed the sensor tags during the manufacturing process.) “Our mandate was to enable tag reads at a rapid walking pace,” he recalls.

The tags are embedded in ceiling sections measuring 4 feet by 8 feet, with one to three tags per section. The read range is about 20 to 30 feet. “After we went onto the roof” and detected a leak, Major says, the building manager called a roofing expert “to confirm that, yes indeed, a pretty inexpensive prototype in an hour had detected something that would have cost tens of thousands of dollars to find.”

In another use case, tags can be retrofitted in a building by being attached to materials via adhesive at such locations as around water heaters or other equipment. Owners of a smart home could simply enter a room with a handheld reader and view, within seconds, whether water has seeped into tagged material, such as floorboards or shower enclosure material.

With software or an app, users could detect which tag has detected that leakage, and thus which material requires a remedy. The software can not only detect when an RFID tag experiences moisture, linked to data about the item to which the tag is attached, but it can also store data indicating that tag’s location, Major explains, based on the GPS location of the reader when the tag is being interrogated.

In the case of concrete, builders can benefit from capturing the conditions of casts after they are poured. As concrete cures, the temperature rises and the moisture level drops. Therefore, the system can identify when concrete is fully dry and ready for the next step in construction processes, such as building on top of a concrete foundation. Builders can also use the tags to identify piping and other items stored in a yard or a warehouse. Often, a storage yard can extend across 30 or 40 acres, making it challenging to quickly identify a single item required for a building project. A Smartrac sensor tag can track conditions, such as a leak in a pipe, as well as that pipe’s location within the storage yard.

Conducting an inventory count throughout a storage yard can cost a company approximately $25,000, SensThys’s customers have reported, while RFID technology could reduce the time and cost of such an inventory-taking process substantially. SensThys and RFID retailer AtlasRFID are now selling a starter kit that includes the moisture tags with a PoE Injector and related cables, as well as the SensArray-Pro reader.

To create the software needed to read sensor data quickly, SensThys completed months of testing and development. “We did 50,000 measurements of the tags to develop these algorithms,” Mitchell states. SensThys hosted an educational webinar in October 2019 to help solution providers understand how the technology could be used.

The SensArray-Pro reader

Although SensThys does not currently sell a handheld reader, Major indicates that the company would like to see the technology utilized with handhelds as well. “If the ecosystem develops,” he says, “and that’s what we want to be a part of, you can imagine there will be people selling handhelds to building inspectors.” SensThys could then help develop the handheld interface, Major notes, allowing building instructors to view and manage the read data. “We want to be supportive of the community. We’d like to see this technology proliferate.” Therefore, the company would work with other reader manufacturers by providing them with software algorithms for use with a handheld device.

There is an innate challenge when it comes to reading sensor data on an RFID tag, Major explains. Typically, a moisture reading can only be captured after multiple interrogations by the reader. With this process, the SensThys reader system can concurrently read sensor tags and their statistically accurate sensor measurements at a rate of 20 to 50 per second. “What’s most important for us is being a big part in enabling sensors,” he states.

The market for RFID-enabled sensor solutions is growing rapidly, Barr says, as many Fortune 1000 companies have already qualified the technology. “Companies are interested [in gaining a] better understanding of their internal processes, and to be able to offer additional services for their end users.” SensThys’s solution is typically integrated with customers’ existing management software, while the firm is also working with resellers and solution providers that may opt to build their own solutions.