Battery-Free Bluetooth Tags?

Over the years there has been a growing use of battery powered low energy bluetooth (BLE) tags to track valuable items throughout enterprises.  Many bluetooth tags have other sensors embedded in them so temperature, motion, humidity, and other functions besides location identification can be obtained.

Bluetooth tags offer the ability to use low-cost bridges/gateways to hear the tags identity and associate its position within IoT asset tracking software.  These readers cost substantially less than other technologies.  

The disadvantage of BLE systems has always been managing and maintaining the batteries inside of the tags.  Those tag batteries typically last less than a year in most circumstances and users must replace the batteries or in some cases replace the tags when the battery drains. 

The size of the tag was also impacted by the battery.  These tags, although not extremely large, are bigger than most passive RFID tags.  Passive RFID tags are usually embedded in labels that are applied to an asset or inventory.

Enter In a New Era

What if you could combine the use of low-cost bridges and gateways associated with BLE tags and the label form of passive RFID tags?  Wouldn’t that make sense and lower system costs?  Absolutely!  

A company has been working on this technology for a few years behind the scenes and has now emerged within the RFID industry.  Enter Wiliot, the company that developed a small microchip the size of most RFID chips that transmit bluetooth signals and can be powered without a battery!

How it Works

Wiliot developed a small microchip that has all the components needed to transmit bluetooth signals, capture temperature and other sensor data in a small package that fits on a label.  The chip also has the ability to “harvest” RF energy to power the tag – providing battery-free bluetooth tags.  The power harvesting occurs using small antennas embedded on a label that captures energy in the 900 MHz and 2.4 GHz (bluetooth frequency) range.  After the chip gets enough power, it uses that power to capture its data and transmit the data using bluetooth signals.  Once it transmits, it needs to harvest more energy to transmit again.

Currently, the power source for harvesting must be within ten meters to get a reliable response from the tags.  That harvesting range should improve over time as the technology develops and more advanced versions are produced.

This technology has been in early-stage adoption by companies testing its capabilities.  One use case that has been disclosed is the use of battery-free bluetooth labels on vials of Covid-19 vaccines. The bluetooth label not only is linked to the vial’s unique identity to provide identification and location information, but it can also measure temperature and determine fill levels.  All of this sensor data is fed back through Wiliot’s cloud services to the customer’s data system for interpretation and decision making.

Pricing Will Improve

As the volume increases, Wiliot expects the battery-free bluetooth label prices to decrease as well.  Currently, the labels cost less than 50 cents each (depending on volume) in smaller quantities but that is expected to drop to less than 10 cents in the next 12 – 18 months. That puts the bluetooth labels close to the same prices as passive RFID tags.

What does it all mean?

With the Wiliot battery-free bluetooth tags, the system dynamics change dramatically.  We can now install bridges and gateways to read tags at about 10% of the cost associated with passive RFID reader systems.  Plus, we get an RFID label with sensor capabilities at the cost of a regular passive label — all using a worldwide frequency standard! Battery-free bluetooth systems allow more use cases to be cost justified with the lower infrastructure costs.  This enables cost effective asset and inventory management on shelves, floor inventory, and across rooms.  We also get the improvements of temperature and other sensor data to make our inventory data become more robust and useful.  Returnable containers carrying food items can be tagged and monitored easily in temp controlled rooms.  Alerts can be created based on temperature changes and location changes all with low-cost infrastructure.

This is the first step in the evolution.  I see more sensors, longer range, and better energy harvesting creating more use cases, better data, and improved visibility to all.

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