Delay line based passive radio frequency identification tags

This work describes the concept, design, fabrication, and characterization of delay-based radio frequency identification (RFID) tags and RFID-based sensor tags, representing a novel RFID technology. The presented delay-based RFID concept is based on the LC-delay-line and transmission-delay-line based approaches. The proposed concept allows the realization of RFIDs and RFID-based sensor tags at any allowed radio frequency, with the limitation of realizing delay elements capable of producing required delays. The RFID configurations presented in this work are for operation at 915 MHz. Simulations are used to design and optimize components and devices that constitute the tags, and to integrate them to realize tags of different configuration. A set of fabrication processes has been developed for the realization of the tag. Characterization and field testing of these tags show that delay-based RFID approach can be used to make passive tags at ultra high frequency (UHF) and other allowed frequencies. Delay-based tags have the advantages of time domain operation, and the feasibility of complying with FCC regulations. However, size, need of isolators and circulator, and design constraints in producing higher number of bits are some of the concerns that need to be further addressed. In summary, this dissertation work presents a viable alternative RFID approach based on the delay line concept. The results obtained show great promise for further development and optimization of this approach for a wide range of commercial applications

Resonant sensors for passive, real-time, and wireless characterization of biological analytes

A passive, low-cost resonant sensor was developed with the potential application of wireless monitoring of hydrolytic enzyme activity in closed systems. The resonators are rapidly prototyped from polyimide substrates (25õm thickness) which are coated with a thin layer of copper (35õm thickness). The patterns of the resonators, which are Archimedean spirals, are drawn on these substrates using an indelible marker with an XY plotter. These substrates are etched with a solution containing hydrogen peroxide and hydrochloric acid in order to remove the undesired copper. The initial resonant frequency of these resonators can be controlled by the Archimedean coil length and pitch size of the spiral. The frequency response window is tuned for the 1-100 MHz range for better penetration through soil, water, and tissue. The resonant frequency can be measured up to 5cm stand-off distance by a 3D-printed coplanar, two-loop coil reader antenna. This reader is attached to a vector network analyzer for monitoring the magnitude of S21 scattering parameter. The central hypothesis is that the Archimedean spiral sensors respond to any change in relative permittivity of the medium in contact with the resonator. This response is represented as a clear shift in the resonant frequency of the resonator. For instance, changing the medium from air to water results in approximately 50MHz redshift in the resonant frequency. In order to measure hydrolytic enzyme activity, the resonant sensors are coated by an enzyme substrate (e.g. hydrogel). The degradation of the enzyme substrate causes a change in the relative permittivity which results in a shift in the resonant frequency (up to 7MHz redshift). By fitting a transport-reaction model, which simulates the radial digestion profile, on the experimental data the activity (turnover rate, or kcat value) of the enzyme is calculated. This approach is used for testing purified Subtilisin A and unpurified bacterial protease samples at different concentrations ranging from 30mg/ml to 200mg/ml with kcat values of 0.003-0.002 and 0.009-0.004 gsubstrate/genzyme per second, respectively. The sensor response rate can be tuned by changing the substrate composition (i.e. changing the gelatin and glycerol plasticizer weight percentage in the hydrogel). Finally, the applicability of these resonant sensors in a real-life problem is demonstrated by wirelessly measuring the proteolytic activity of farm soil with a measured kcat of 0.00152 gsubstrate/(gsoil÷s) using 3D-printed plastic cases

Monitoring cold chain logistics by means of RFID.

Every day, millions of tons of temperature sensitive goods are produced, transported, stored or distributed worldwide. For all these products the control of temperature is essential. The term “cold chain” describes the series of interdependent equipment and processes employed to ensure the temperature preservation of perishables and other temperaturecontrolled products from the production to the consumption end in a safe, wholesome, and good quality state (Zhang, 2007). In other words, it is a supply chain of temperature sensitive products. So temperature-control is the key point in cold chain operation and the most important factor when prolonging the practical shelf life of produce. Thus, the major challenge is to ensure a continuous ‘cold chain’ from producer to consumer in order to guaranty prime condition of goods (Ruiz-Garcia et al., 2007).These products can be perishable items like fruit, vegetables, flowers, fish, meat and dairy products or medical products like drugs, blood, vaccines, organs, plasma and tissues. All of them can have their properties affected by temperature changes. Also some chemicals and electronic components like microchips are temperature sensitive

Pushing the Physical Limits of IoT Devices with Programmable Metasurfaces

Small, low-cost IoT devices are typically equipped with only a single, low-quality antenna, significantly limiting communication range and link quality. In particular, these antennas are typically linearly polarized and therefore susceptible to polarization mismatch, which can easily cause 10-15 dBm of link loss on communication to and from such devices. In this work, we highlight this under-appreciated issue and propose the augmentation of IoT deployment environments with programmable, RF-sensitive surfaces made of metamaterials. Our smart meta-surface mitigates polarization mismatch by rotating the polarization of signals that pass through or reflect off the surface. We integrate our metasurface into an IoT network as LAMA, a Low-power Lattice of Actuated Metasurface Antennas, designed for the pervasively used 2.4 GHz ISM band. We optimize LAMA's metasurface design for both low transmission loss and low cost, to facilitate deployment at scale. We then build an end-to-end system that actuates the metasurface structure to optimize for link performance in real time. Our experimental prototype-based evaluation demonstrates gains in link power of up to 15 dBm, and wireless capacity improvements of 100 and 180 Kbit/s/Hz in through-surface and surface-reflective scenarios, respectively, attributable to the polarization rotation properties of LAMA'S metasurface

WSR: A WiFi Sensor for Collaborative Robotics

In this paper we derive a new capability for robots to measure relative direction, or Angle-of-Arrival (AOA), to other robots operating in non-line-of-sight and unmapped environments with occlusions, without requiring external infrastructure. We do so by capturing all of the paths that a WiFi signal traverses as it travels from a transmitting to a receiving robot, which we term an AOA profile. The key intuition is to "emulate antenna arrays in the air" as the robots move in 3D space, a method akin to Synthetic Aperture Radar (SAR). The main contributions include development of i) a framework to accommodate arbitrary 3D trajectories, as well as continuous mobility all robots, while computing AOA profiles and ii) an accompanying analysis that provides a lower bound on variance of AOA estimation as a function of robot trajectory geometry based on the Cramer Rao Bound. This is a critical distinction with previous work on SAR that restricts robot mobility to prescribed motion patterns, does not generalize to 3D space, and/or requires transmitting robots to be static during data acquisition periods. Our method results in more accurate AOA profiles and thus better AOA estimation, and formally characterizes this observation as the informativeness of the trajectory; a computable quantity for which we derive a closed form. All theoretical developments are substantiated by extensive simulation and hardware experiments. We also show that our formulation can be used with an off-the-shelf trajectory estimation sensor. Finally, we demonstrate the performance of our system on a multi-robot dynamic rendezvous task.Comment: 28 pages, 25 figures, *co-primary author

Sky-Farmers: Applications of Unmanned Aerial Vehicles (UAV) in Agriculture

Unmanned aerial vehicles (UAVs) are unpiloted flying robots. The term UAVs broadly encompasses drones, micro-, and nanoair/aerial vehicles. UAVs are largely made up of a main control unit, mounted with one or more fans or propulsion system to lift and push them through the air. Though initially developed and used by the military, UAVs are now used in surveillance, disaster management, firefighting, border-patrol, and courier services. In this chapter, applications of UAVs in agriculture are of particular interest with major focus on their uses in livestock and crop farming. This chapter discusses the different types of UAVs, their application in pest control, crop irrigation, health monitoring, animal mustering, geo-fencing, and other agriculture-related activities. Beyond applications, the advantages and potential benefits of UAVs in agriculture are also presented alongside discussions on business-related challenges and other open challenges that hinder the wide-spread adaptation of UAVs in agriculture

Flexible electronics: The next ubiquitous platform

Thin-film electronics in its myriad forms has underpinned much of the technological innovation in the fields of displays, sensors, and energy conversion over the past four decades. This technology also forms the basis of flexible electronics. Here we review the current status of flexible electronics and attempt to predict the future promise of these pervading technologies in healthcare, environmental monitoring, displays and human-machine interactivity, energy conversion, management and storage, and communication and wireless networks

Development of paper-based microfluidic devices for environmental and food quality analysis, The

Includes bibliographical references.2016 Fall.Providing safe and nutritious food and water, both domestically and internationally, has long been a goal for improving global health. Recent legislations enacted within the United States have enabled government agencies to further regulate agricultural and industry standards, necessitating the need for more preventative approaches with regards to food and beverage quality and safety. Increasing detection speed and enabling field and production detection of point-source contamination are crucial to maintaining food and beverage safety as well as preventing detrimental disease outbreaks, such as those caused by bacterial contamination. The development of simple, inexpensive, and portable methods for detecting contamination indicators are key to reaching this goal. Moreover, recent developments into microfluidic approaches for analysis have shown great promise as platforms for providing faster simplified methods for detection. The work conducted within this dissertation focuses on the development of simple, inexpensive and disposable platforms for colorimetric and electrochemical analysis of food and beverage quality. Aside from more commonly studied polymer-based devices, recent advances in paper-based diagnostics have demonstrated use as an analytical platform capable of self-pumping, reagent storage, mixing, and implementation of various detection motifs. Herein, the development of microfluidic paper-based analytical devices (μPADs) is presented as a platform for the colorimetric detection of bacteria in food and water samples. Initial work was conducted for the paper-based, colorimetric detection of Listeria monocytogenes, Salmonella Typhimurium, and E. coli O157:H7 bacteria species, all of which have been associated with fatal, multistate food- and waterborne outbreaks. Detection was performed on ready-to-eat meats using a swabbing technique to collect and quickly culture surface contamination of bacteria using enzymatic assays within paper-based microwells. A scanner was used for imaging followed by use of image analysis software for semi-quantitative measurement determination. This method was further applied to the detection of bacteria in irrigation water, a known source of foodborne contamination, using a 3D-printed filter for collection and culture of bacteria present in low concentrations within water. Although colorimetric detection offers a simple, visual detection method, electrochemistry is an alternative, sensitive and portable method for detection. Use of common office materials such as transparency film and copy paper, as well as laboratory filter papers were studied and developed for optimal electrochemical platform performance. The use of microwires as a simple fabrication method for incorporating metallic or modified metallic electrodes into electrochemical paper-based devices (ePADs) was also developed. Electrochemical behavior in both well-based and flow-based ePADs was studied and implemented for the nonenzymatic detection of sugars in beverages using copper oxide modified microwires, and for the in-line flow detection of enzymatic assays using gold and platinum microwire electrodes respectively. Furthermore, the fast, inexpensive, and simple fabrication of carbon stencil-printed electrodes (CSPEs) on transparency film were demonstrated for the electrochemical detection of E. coli and Enterococci bacteria species, both indicators of fecal contamination, in food and water samples using enzymatic assays. These same assays could also be determined colorimetrically and a more portable cell phone was used to image and wirelessly send paper-based well-plate results. This method was developed for use in place of a more bulky and expensive plate reader, and results were used for comparison to electrochemical detection of bacteria from a single assay