RF Device Charges Wirelessly, Acts as RFID Reader

Published: July 28, 2023

Powercast’s Ubiquity transmitter and receiver modules allow device manufacturers to build low-cost wireless charging and two-way communication into everything from electric toothbrushes to home security systems

Wireless charging technology company Powercast has released a new RF-based over-the-air wireless power system that enables radio frequency identification (RFID) transmission, as well as a power supply for wireless Internet of Things (IoT) products, such as those used in appliances, game systems or smart speakers. The solution, known as Ubiquity, is designed to allow device manufacturers to build wireless power-harvesting functionality into their products, with the potential for transmitting data via 902 to 928 MHz.

Users could potentially employ low-cost RF networks in homes or businesses that could accommodate a variety of RF-receiving tags, sensors and devices. The solution consists of a Ubiquity transmitter that sends RF signals over the air, as well as a receiver that is embedded in end devices. These include sensors that receive RF transmissions, harvest energy and convert it into DC power, according to Jason Gill, Powercast’s director of research and development.

Developers or manufacturers can build Ubiquity RF transmitters into their appliances or products to transmit power to other devices, via a reference design that enables integration of the electronics into their circuit boards. Alternatively, companies could acquire Ubiquity transmitter modules and drop them into existing electronic devices to make them RF-enabled.

On the other end of the solution is the receiver. Powercast sells its Powerharvester PCC110 receiver chip, which the company says can be built in along with a small antenna to an end device such as a sensor, tag or small electronic product for a cost of about $1.00. The company recently teamed up with Kyocera AVX to offer sustainable, battery-free solutions featuring the PCC110, capable of harvesting power from RFID readers.

Powercast has spent more than a decade developing and selling RF-charging-enabled technology and RFID systems (see Powercast PCT100 Tag Employs RF Interrogator Energy to Transmit Sensor Data and Powercast Debuts Energy-Harvesting Wireless Sensor System). By providing a solution that can both charge and read data at a low cost, the company intends to help manufacturers create IoT devices capable of enabling connectivity that had previously required more expensive RFID or Bluetooth Low Energy (BLE) infrastructure.

Charging Devices Wirelessly

For power harvesting, the Ubiquity transmitter provides up to 1 watt (3 watts effective isotropic radiated power) over the air, and automatically charges multiple devices with the PCC110 receiver as they enter its charging zone. Unlike standard wireless charging systems, no charging mats are required. Ultra-low-power devices like IoT sensors could charge at a distance of up to 120 feet from the transmitter, while more power-hungry devices such as headphones would need to be at a much closer range and could use the technology as supplemental charging.

The solution was demonstrated recently at the CES 2023 trade show, in a simulated home living room and bathroom environment. During the demonstration, the system is being used in scenarios in which the transmitters could automatically charge and monitor the conditions and locations of multiple devices within a room. In the bathroom, for instance, a single transmitter charges all low-power devices, like toothbrushes and shavers.

RF-powered products eliminate cords around water, as well as the need to open a device to change batteries, says Andy Peacock, Powercast’s marketing director. This reduces the risk of electric shock for users, he explains, while decreasing the potential for corrosion to a device with a chamber in which batteries are stored. RF also eliminates the inconveniences of electric toothbrushes, he adds, stating, “No more dock to accumulate grime, and no more need for batteries that often corrode from water seeping in.” Standard wireless charging is accomplished via magnetic induction, with a device sitting on the wireless charger, typically built into a charging mat.

“What tends to happen,” Gill says, “is I can send a decent amount of power to charge your phone but you can’t go very far away from the charger.” The Ubiquity system employs a different approach, as it deploys RF-based wireless power over the air, similar to the frequency used for UHF RFID tag reading. Devices could utilize the transmission strictly to harvest power for their own operation, or they could backscatter a signal that would include data that would be read by the transmitter.

An Alternative to Standard RFID

“The price point of most RFID readers was higher than what we believe the consumer market would want,” Peacock says, “so a couple of years ago we made our PowerSpot transmitter that retailed for about $100.” The PowerSpot solution sends power to devices, then uses Bluetooth as a communication network back from the device being charged.

“What we really wanted to do [next],” Peacock says, “was get that price point way lower than what it was for the PowerSpot.” He notes that consumer markets are more cost-sensitive than most RFID applications, so the technology’s price needed to be a fraction of that amount. “So we developed a module and a reference design for what we’re calling the Ubiquity transmitter.” It integrates with a device’s own power system and wireless connectivity, while also providing RF charging and two-way communication.

The transmitter module includes a radio andamplifier. Manufacturers will add an antenna with guidance from Powercast. The module can accomplish the necessary frequency hopping to connect with the devices within its range, leveraging its power amplifier to increase signal transmission. A built-in data-read circuit extracts the information that the receiver backscatters to the transmitter, interfaces with a microcontroller to interpret that data. The transmission would not work with standard EPC UHF RFID tags, Gill says, but only with Powercast’s own receiver modules. He likens the receivers to the size of pepper flakes and says the cost is expected to average about a dollar.

In a typical use case, the transmitter — which could be plugged into an outlet or use another device’s built-in power — sends a transmission periodically. If no response is received, it knows there are no devices that require charging, and thus goes dormant. However, a backscatter response could indicate a product in need of a charge, fundamentally acknowledging “Yes, I’m here. Give me power.” The transmitter would then continually send its RF energy.

The system could be designed so that a receiver would respond with its unique ID number and data related to its power level. In this case, the transmitter could continue powering until the device indicated it was fully charged, then shut itself off. The technology could also help users understand the battery levels of multiple products around a single transmitter. For instance, the Ubiquity transmitter could be built into a device with an LED screen that would display the detected charge levels of all wireless Ubiquity-enabled devices within range. Users could also deploy the system with sensors.

Multiple Charging Applications

If a battery-powered or battery-free sensor device leveraged the Ubiquity system, it could transmit such information as ambient temperature, or whether a home’s window was open or closed. The system’s range would be device-specific, Gill says. In the case of a low-duty cycle sensor that transmits once every half hour or so, the range could be as long as 120 feet. “But if you’re looking to do major charging, such as headphones,” he notes, then a shorter range would require a tabletop application.

For example, the transmitter could be built into a nightstand, or into an entertainment center in which all charging devices are within close range. Powercast estimates that the transmitter electronics could be built into a device at a cost of approximately $5 using the reference design. In the bathroom simulation at CES, the company has a small Ubiquity transmitter in the wall outlet, similar in size to an air-freshening plug-in, which overlooks a double-sink vanity. The company provided six wireless toothbrushes that all have the receiver chip and antenna built in.

In a home’s living room, a transmitter could be set up to charge and communicate with a variety of household items, such as key fobs or RF tags that could be placed in wallets or other items users want to keep track of. The transmission module could be built into a home appliance, such as a smart television or computer device, and it could then wirelessly charge related end point, such as keyboards or gaming remotes.

In addition, the system could communicate with IoT devices, including plant sensors that track the moisture level of a potted plant, or leak-detection sensors situated under a sink. In a commercial application, the technology could detect the need to refill soap dispensers or recharge batteries in public bathrooms.

Adding Devices Over Time

Once the technology is in place, the company reports, users could add additional receiver devices. “You can add anything that would work in that atmosphere,” Gill says, “and they could all get charged from the same device.” The bathroom is a great use case, he explains, due to the prevalence of battery-operated or wireless devices that do not require a large amount of charge, are only used a few times a day, and remain within close range of a transmitter due to the typically small size of bathrooms.

Data captured from a Ubiquity system could be forwarded to a server via a manufacturer’s choice of Bluetooth or Wi-Fi connectivity. “We’ve left that up to the manufacturer’s specific decisions,” Peacock says. Since the technology was just released this week, the company is now entering into discussions with early adopters. “We anticipate a huge demand, and we’re teasing it with a lot of companies that would want to use something like this.”

The system is not designed for charging power-hungry devices like smartphones or tablets, Gill notes. For such devices, however, Ubiquity could be used alongside existing charging systems. “The plug in the wall is going to be the fastest,” he states, “and people are used to that kind of speed.” But to top off power overnight or keep the phone charged, he adds, Ubiquity could be deployed in tandem with other technologies.


Key Takeaways:

  • The Ubiquity device can potentially charge wireless products at a range of up to 80 to 120 feet, as well as receive data response from a device, via a UHF transmission at 902 to 918 MHZ.
  • The system is intended to open up IoT solutions, smart-home applications and other systems for which wireless devices require power and monitoring.