The embedded slides were presented by Powercast at the Sensors Expo in Chicago on June 6, 2012. The presentation covers how RF power harvesting enables passive wireless sensor tags (PWST) and high-function RFID. What is high-function RFID? There’s no official definition, but view it as a class of devices that uses RFID for communications but also includes numerous other components for advanced functionality. The additional components may require significantly more power than is available from a regular RFID chip, and a battery may not be desired. RF power harvesting from and RFID reader can provide the extra power needed for these devices.
Powercast designed a high-performance 915MHz antenna to fit onto a credit card sized device. The antenna can be connected directly to a Powerharvester module and it uses about 40% of the PCB area. When used for Powerharvesting this design is for receiving only and does not support data transmission. Contact Powercast for more information.
Powercast recently presented (09/21/2011) at the Remote Monitoring & Control Conference in Nashville, TN. The cost of installing wiring can range from $200 per device to >$1000 per foot in some industrial environments. In either case, wireless power transmission over distance using RF energy can potentially be a suitable alternative to running wires or replacing batteries.
An article by Powercast titled “RF Energy Harvesting and Wireless Power” was published by Electronic Products.
“The market growth of low-power wireless devices particularly sensors is driving tremendous interest in using energy sources that can power the devices autonomously. The cost of running wires and the future cost of replacing batteries have discouraged users from widely deploying a verity sensor-based devices.
While solar has been widely used for years to power remote devices, several other types of energy-harvesting approaches have emerged for micro-power applications including vibration, thermal, mechanical, and RF. Of these technologies, RF energy is the only one that can provide either an intentional or ambient power source for wire-free or battery-free applications.”
Powercast exhibited at the Sensors Expo 2011 and demonstrated using RF energy harvesting to wirelessly charge credit card size devices. The devices are representative of high function, rechargeable smart cards and contained rechargeable thin-film batteries - CYMBET EnerChip, Infinite Power Solutions THINERGY, and STMicroelectronics EnerFilm.
The video below shows the rechargeable smart card devices receiving charge from an RF transmitter. The transmitter was on the floor under the table.
An article in RFID Journal recently reviewed the Powercast Lifetime Power Wireless Sensor System which has battery-less wireless sensors (passive wireless sensor tags) powered by RF energy.
“Powercast Corp. is marketing active RFID sensor tags that harvest power from RF signals. The system includes an RF transmitter that provides power signals to sensor tags, and a gateway that receives information transmitted by those tags. The company’s focus is on developing solutions for the wireless transmission of sensor data, such as what is required by data centers. In this case, rather than using wired sensors or traditional active RFID tags to send sensor data regarding a room’s conditions, the Powercast system simply uses continuous RF signals to charge a battery or capacitor built into a sensor tag. The solution, known as the Lifetime Power Wireless Sensor System, targets the heating, ventilating and air conditioning (HVAC) sector, as well as other building-controls industries, by providing a solution for acquiring data from sensors for heating and air-conditioning, lighting controls, access controls or other building automation.”
Powercast has released a battery-less, wirelessly-powered sensor system for building and industrial automation - the Lifetime Power® Wireless Sensor System. The sensor units can be powered at a range of 60-80 feet (18-24 m) from Powercast’s 3W, 915MHz transmitter (TX91501). The initial sensor unit is for temperature and humidity and is to be followed by other types such as CO2, light, and motion.
Powercast Lifetime Power® Wireless Sensor System
The access point (WSG-101 BAS gateway) supports up to 100 sensors and 800 sensor points for large-scale and high-density deployment of sensors. The sensors are battery-free and operate when sufficient charge is stored to take sensor readings and send a data packet. Wireless communication from the sensor nodes to the access point is 2.4GHz using industry-standard 802.15.4 radios. The BAS gateway supports several physical interfaces and a range of BAS protocols to interface with nearly every major type of wired BAS network, including BACnet, Modbus, Metasys N2, and LonWorks.
The video below demonstrates how Powercast’s wireless power technology charges multiple devices simultaneously, and in this case a wireless keyboard, a wireless mouse, and a wireless game controller. The amount of power being delivered to these devices is in the low mW range.
Some applications can be powered directly from the transmitter, but for most consumer electronic devices trickle-charging a battery will be more appropriate.