Bio: Christopher R. Valenta is a Ph.D. student in Electrical Engineering at the Georgia Institute of Technology. As a member of ‘The Propagation Group,’ Christopher helped to commercialize the first 5.8 GHz backscatter sensor system for use in high-voltage environments and has developed numerous technologies for RFID-enabled sensors.
Group website: www.propagation.gatech.edu
1.) Why RFID for sensing?
Radio frequency Identification (RFID) is beneficial for sensing applications because of the simplistic, low-cost (few cents), and low-profile design. Passive, or battery-free, tags harvest energy from the environment and are able to power sensors and the RFID chip itself. This operation is possible as there is no transmitter on the tag. Instead, the RFID relies on reflecting radio waves sent from an RFID reader, also known as backscatter communication. This allows the RFID to send data with powers down to pico-Watts per bit.
2.) Tell us a little about your work in RFID-enabled sensors at Georgia Tech and elsewhere?
Our group [The Propagation Group] at Georgia Tech is one of the only labs in the world who work with 5.8 GHz RFID. The majority of RFID/RFID-enabled sensor work occurs in the high frequency (HF) and ultra-high frequency (UHF) bands. Since 5.8 GHz is relatively unused, we’ve had to build our entire RFID system from the ground up. By doing this, we’ve been able to exploit some of the benefits of microwave frequencies and cater the design towards RFID-based sensor applications.
3.) What makes 5.8 GHz unique in terms of design and application?
5.8 GHz has a range of benefits due to its short wavelength and regulatory status. First, the short wavelength allows us to make very small antennas compared to lower frequencies. Since antenna size typically dominates the sensor size, our sensors can be smaller than ones at lower frequencies. Additionally, 5.8 GHz is an international band with a large available bandwidth. Other RFID bands vary from country to country so readers have to cater to this.
4.) What’s the 5.8 Ghz sweet spot or killer application?
5.8 GHz could have applications in a variety of areas. Situations that require a tag have a small footprint would be especially suited for microwave RFID. Also, high data rate applications would benefit from the large available bandwidth available. Our research has also noted the unique plasma penetrating ability of 5.8 GHz RFID which makes it suited for high-voltage monitoring applications in the smart grid.
5.) What do you see as the future of this space? Do you notice any identifiable gaps in the industry that will require further R&D?
The biggest hurdle right now for 5.8 GHz is the lack of inexpensive semiconductor processes. While there are microwave parts available for RFID, they are typically expensive, inefficient, and incompatible with modern CMOS processes. Thus, there are hurdles in commercializing a low-cost, microwave RFID integrated circuit for the mass market.
6.) What do you think are the hottest technologies in the world of wireless sensor networks?
There’s been a lot of focus in the RFID and sensors community working with nano materials. Merging these technologies together is bound to have a tremendous impact on the military, healthcare, and consumer market because of the unique sensing abilities that nano materials can bring. There has also been a lot of attention towards localization of RFID-enabled sensors. Being able to simultaneously record sensor data and position can be extremely beneficial in certain applications.
7.) What gets your team most excited moving forward?
Our lab is motivated by the uniqueness of the research we are pursuing. There aren’t many other universities or research groups working at 5.8 GHz, so we real feel like pioneers in this regard.
