Passive Sensors - A Guide To Passive Sensing Tags

April 9, 2021

Here at Metalcraft we produce many types of tags and labels, and we’ve developed many custom products to meet ID challenges. We know the value of a great tag. So, we are eager to share promising new technology using passive sensors.

Monitoring changing temperature, moisture, pressure

Monitoring with wireless RFID sensors has been around for some time – using battery-powered sensors to monitor and broadcast environmental changes to RFID readers. Wireless sensor tags are widely used for remote, automatic measurements, detecting changes in moisture, temperature, pressure and more.

However, sensor technology is at the edge of a new level of connectivity – an ‘Internet of Everything’ where we can use passive RFID technology to sense and monitor in powerful new ways.

Active vs. Passive

An active RFID tag uses battery power to broadcast data, either as a transponder replying to a signal or as a beacon actively sending out its information. The tag’s battery affords long read ranges and large memory in exchange for a large form factor and short lifespan. The battery can also power on-tag sensors detecting moisture, temperature and other environmental changes. But when the battery fails, the tag needs to be replaced, and these tags are expensive.

There are Battery-Assisted Passive (BAP) RFID tags, too. They can also use an internal battery to power a sensor monitor, but they do not actively send a signal, instead sending data when requested by an RFID reader or logging data until read. These are slightly smaller and less costly compared to active sensor tags. Still, BAP tags need to be replaced when the battery fails.

Passive sensor tags are the new technology, adding the ability to sense without a battery retains the advantages of passive tags without sacrificing read range. The core of the technology is the integrated circuit detecting environmental changes and transmitting information to the reader using RF energy.

Advantages of RFID passive sensor tags

Metalcraft’s new passive sensor tags hold tremendous advantages over existing wireless sensors products.  Passive sensors are much smaller, thinner and more flexible than battery-powered sensors allowing them to be utilized in a broader array of applications.  They are more economical due to of their construction requiring less labor and no battery maintenance or replacement. In fact, their low cost makes passive sensor ideal for disposable or limited use applications. These are set-and-forget sensors, allowing more sensors in more places without substantial costs in the tag technology.

How do wireless passive sensors work?

We are making durable passive RFID sensor tags that work using standard UHF frequencies and do not sacrifice read range. Passive sensor tags are primarily a chip and antenna; the chip’s integrated circuit harvests energy from the UHF reader to transmit changing antenna impedance correlated to pressure, temperature or moisture level. The change is captured with an EPC Gen 2 compliant reader and interpreted with a software application. Tags can be affixed to a range of surfaces and tuned to specific applications.

What can you do with passive sensing?

Because these sensor tags are simple and inexpensive they open up a broad range of new uses beyond existing sensor applications.  With the ability to access quality-related data using large numbers of wireless, maintenance-free sensors, important decisions that protect people and equipment can be made pro-actively and with confidence.

Sensing can solve problems for manufacturing, agricultural, healthcare, construction and retail environments. From predictive maintenance to leak detection to incontinence management and far beyond, we are going to see Internet of Things applications explode with this new technology.

Bottom line savings from passive sensing

Investing in passive sensors creates powerful new efficiency and competitive advantage; it’s going to be easier to provide quality data that keeps food fresh, equipment safe and much more. This new class of battery-free and maintenance-free wireless sensor tags expands the sensing opportunities and lowers the cost of ownership.

As you consider the value of wireless sensing for your business, know that Metalcraft is ready with affordable, durable passive RFID sensor tags. We encourage you to contact a Metalcraft ID Specialist at 800-437-5283 to explore this new technology today.

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