News & HighlightsRadio Frequency Identification at the University of PittsburghContact: Marlin H. Mickle, email: mickle@ece.pitt.edu The ability to locate an individual person while simultaneously observing their vital signs anywhere in the world was impossible a short time ago. Autonomous un-tethered wireless technology presents major challenges in the areas of technology and regulation, and there are also serious social implications to consider. As the use of this technology proceeds, the economic, social, legal and regulatory issues will place extreme pressures on future technological development and application. The School of Engineering of the University of Pittsburgh is committed to the science, engineering and technology of autonomous un-tethered wireless devices and infrastructure. The main effectors of change in RFID, sensing and ad hoc technological application requirements are important to this research effort. The competency required in cutting edge autonomous un-tethered wireless devices and their last hop connections are a major research focus in the School of Engineering. The University of Pittsburgh has developed a technology termed Active Remote Sensing (ARS) to power these autonomous devices and to communicate with a base station (reader) receiver. The ARS technology harvests energy from a directed source or ambient and converts it to a DC voltage to power on-board circuits and sensors including a communications device. The classical backscatter technology of RFID is well-known and is commercially available from a number of vendors. The following discussion is to simply relate ARS energy harvesting technology to backscatter RFID technology and establish a context to illustrate the ARS flexibility as a function of the system specifications and the environment in which a particular device is to operate. Specific questions can be directed to the above contact point. An ARS device derives its power (energy) from the ambient environment, takes a sensor reading, and communicates its identity and the sensor reading to a receiver. The ambient can be enhanced by providing Radio Frequency (RF) powering energy termed directed energy. A major ARS feature is that the device requires no battery, wires, fuel cell, etc. Thus, it is un-tethered both physically and in time (maintenance). It is not necessary to employ the sensor function as a part of the device in which case the ARS device becomes an RFID tag. As an RFID device (tag), it has the advantage of flexibility and a favorablesignal to noise ratio. An ARS device has an "infinite" shelf life determined only by the lifetime of the electronic components used in its manufacture - not on an energy storage device. In a more practical vein, given a sensor to be powered and communicated with wirelessly, the power budget consists of that power required; (a) for the sensor and associated support circuitry, and (b) that required for the transmitter to satisfy the receiver power/sensitivity requirements. Based on this budget, the problem is one of finding an operating point within; (1) the space of all possible powering frequencies, (2) a set of antennas that will satisfy the size/structure specifications; (3) the set of receiver/charge pump (or alternative conversion device) combinations that can be matched to the antenna; and (4) the range of RF power/energy values of sufficient magnitude to provide the required power/energy at the antenna of (2). In each of the items (1) through (4), there is a bounded range of possibilities in each item although their intersection may be null in which case there is no solution. Our research program is directed to solving specific problems in these areas and advancing the fundamental science supporting this technology. |
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