Chipless RFID sensor tag system with microstrip transmissionline based ID generation schemes

This dissertation presents a chipless radio frequency identification (RFID) sensor tag system consisting of passive chipless RFID sensor tags and specialized reader. The chipless sensor tags are fabricated on a flexible substrate and contain an ID generation circuit, a sensor, and a microstrip antenna. The ID generation circuit consists of meandered microstrip transmission lines and uses a novel reflection and delay based ID generation scheme. The scheme, using an input RF pulse, constructs an on-off keying (OOK) or pulse position modulated (PPM) signal pattern representing a unique ID code. Two transmission lines and OOK representation are used and the generation of ten different ID codes are demonstrated. The integrated ID generation circuit, sensor, and antenna use a single transmission line and PPM representation, and demonstrate the generation of eight different ID codes. However, the presented schemes allow the generation of higher combinations of bits. A practical method to measure radar cross section (RCS) parameters of antennas that provides complete and more accurate information on scattering properties of antennas, essential for chipless sensor tag design, is presented. The new method uses minimum mean square error estimation solution of a derived received backscattered signal power equation and provides load independent structural-mode RCS, antenna-mode RCS, and relative phase factor of the measured antenna. Two configurations of the chipless sensor tags configuration-I (conf-I) and configuration-II (conf-II) are presented. In conf-I tags, sensors are connected as a load to the antenna and the sensor information is amplitude modulated in the backscattered signal. The testing with conf-I temperature sensor tag resulted in a 28% amplitude change when the temperature at the tag changes from 27°C to 140°C. In conf-II tags, sensors are connected as load to the ID generation circuit and the sensor information is phase modulated in the antenna-mode scattered signal. With the conf-II ethylene sensor tag, a phase change of 33° is observed when the ethylene concentration at the tag changes from 0 to 100 ppm. The specialized reader system is comprised of an analog reader that wirelessly communicates with the sensor tags and a single board computer that computes the sensor information from the received signal. The reader system constructs a 96 bit serialized global trade item number (SGTIN-96) electronic product code (EPC) format unique RFID tag data frame, including 16 bit sensor information, and makes the information available on a secure web interface accessible from cyberspace. The presented sensor tag system has the advantages of passive and chipless sensor tag operation, while offering a wide range of sensors types for integration. Moreover, it offers a viable alternative solution to existing active as well as passive RFID sensor tag systems (eg. SAW based RFID sensor tag systems)

Poly(vinylidene fluoride-hexafluoropropylene) polymer electrolyte for paper-based and flexible battery applications

Paper-based batteries represent a new frontier in battery technology. However, low-flexibility and poor ionic conductivity of solid electrolytes have been major impediments in achieving practical mechanically flexible batteries. This work discuss new highly ionic conductive polymer gel electrolytes for paper-based battery applications. In this paper, we present a poly(vinylidene fluoride-hexafluoropropylene) (PVDH-HFP) porous membrane electrolyte enhanced with lithium bis(trifluoromethane sulphone)imide (LiTFSI) and lithium aluminum titanium phosphate (LATP), with an ionic conductivity of 2.1 × 10−3 S cm−1. Combining ceramic (LATP) with the gel structure of PVDF-HFP and LiTFSI ionic liquid harnesses benefits of ceramic and gel electrolytes in providing flexible electrolytes with a high ionic conductivity. In a flexibility test experiment, bending the polymer electrolyte at 90° for 20 times resulted in 14% decrease in ionic conductivity. Efforts to further improving the flexibility of the presented electrolyte are ongoing. Using this electrolyte, full-cell batteries with lithium titanium oxide (LTO) and lithium cobalt oxide (LCO) electrodes and (i) standard metallic current collectors and (ii) paper-based current collectors were fabricated and tested. The achieved specific capacities were (i) 123 mAh g−1 for standard metallic current collectors and (ii) 99.5 mAh g−1 for paper-based current collectors. Thus, the presented electrolyte has potential to become a viable candidate in paper-based and flexible battery applications. Fabrication methods, experimental procedures, and test results for the polymer gel electrolyte and batteries are presented and discussed

Paper-Based Flexible Lithium-Ion Batteries

Paper-based flexible batteries have a wide range of applications in paper-based platforms, including in paper electronics, packaging, product displays, greeting cards, and sensors. This poster will present lithium-ion batteries using flexible paper-based current collectors. These current collectors were fabricated from wood microfibers that were coated with carbon nanotubes (CNT) through an electrostatic layer-by-layer nanoassembly process. The use of paper-based current collectors provides flexibility and improved electrode adhesion. Electrodes were fabricated by casting thin layers of lithium titanium oxide, lithium cobalt oxide or lithium magnesium oxide on the conductive paper. Half-cell and full-cell devices were fabricated and tested. The results show that the presented batteries use reduced mass loading of carbon nanotubes (10.1 μg/cm2) compared to CNT film based batteries. Experimental capacities of the half-cell devices were measured to be 150 mAh/g for lithium cobalt oxide, 158 mAh/g for lithium titanium oxide, and 130 mAh/g for lithium magnesium oxide. Device designs, fabrication processes of paper-based current collectors, electrodes, and batteries, and further experimental results, including solid electrolytes, will be presented

SYNTHESIS AND FUNCTIONALIZATION OF CIGS NANOPARTICLES FOR LBL DEPOSITION

poster abstractCopper Indium Gallium Diselenide (CIGS) solar cells have been used widely in thin film solar cells due to their high attainable efficien-cy and tunable band gap. The cost of solar cell manufacturing needs to be further reduced to make CIGS solar cells economically viable. The main objective of this research is to repeatedly and accurately synthe-size CIGS nanoparticles in a desired ratio to allow for an efficient band gap and dispersion in an aqueous solution for Layer-by-Layer (LbL) nanoassembly. CIGS nanoparticles have been synthesized by arrested precipitation in Oleylamine solution. The particles were purified utiliz-ing chloroform, ethanol, and water via centrifugation. The purified na-noparticles were down to a size of 15 nm with average size of 60 nm. A ligand exchange was performed to remove the capping agent, Oleylamine, and replace it with 11-mercaptoundecanoic acid, a thiol ligand. The thiol ligand used had charged functional groups resulting in the functionalized particles with expected high negative zeta potential for stable dispersion. Lastly, the nanoparticles were analyzed through the utilization of X-ray diffractive spectroscopy (XRD), transmittance spectroscopy, energy-dispersive x-ray spectroscopy (EDS) and a scan-ning electron microscope (SEM). Using the oppositely charged disper-sion in aqueous solutions, multiple size-controlled layers of CIGS can be obtained using Layer-by-Layer nanoassembly, creating a solar cell. The synthesis, characterization and functionalization results will be presented in the poster

FABRICATION OF A THIN FILM SOLAR CELLS USING LAYER BY LAYER (LBL) NANOASSEMBLY OF COPPER INDIUM GALLUIM SELENIUM (CIGS) NANOPARTICLES

poster abstractCopper Indium Gallium Selenium (CIGS), a p-type semiconductor material with a tunable band gap, has been broadly studied for high efficiency solar cells as a viable sustainable energy source. Production of CIGS nanoparticles gives the ability of fabricating thin, light, and flexible solar cells. However, the current fabrication technologies of such devices are still very costly. This poster presents the synthesis and functionalization of CIGS nanoparticles and proposes Layer-by-Layer (LbL) nanoassembly process, as a low cost method, to fabricate thin films for solar cell applications. The results show that the synthesized CIGS particles have 1.3 ev band gap and 30 nm diameter in av-erage. These particles were later coated with polymers to provide alternative opposite surface charges suitable for LbL process. Deposition of 20 layers of the particles on indium tinoxide (ITO) coated glass formed a thin film with 220 nm thickness. The measured current voltage (I-V) characteristic of the film gave resistivity of 7.9 MΩ.m in dark and 2.25 MΩ.m under light illumina-tion. A prototype solar cell made out of the film resulted in short circuit cur-rent density (JSC) of 0.3 mA/cm2 and open circuit voltage (VOC) of 0.7 V

Breast Cancer Detection via Microwave Imaging

poster abstractBreast cancer is one of the major common diseases among women and takes about 40,000 lives every year. Early detection of breast cancer greatly increases the chance of survival. The norm for today’s detection of breast cancer consists of mammograms, magnetic resonance imaging (MRI), and ultrasonic examination. Unfortunately, the process is a fraction of completeness despite its feeling of discomfort, high cost, and exposure to ionizing radiation which poses cumulative side effects respectively. The present research investigates the efficiency and implementation of microwave imaging to be used in the detection of breast cancer. Microwave imaging (MWI) is a process that illuminates the breast with microwave signals, and receives and analyses scattered signals for breast cancer detection and imaging. The electromagnetic waves that are scattered within the breast provide information that are transmitted and received via microstrip patch antennas, providing an image of detected lesions. In the presented poster, design of a patch antenna and simulation results are presented. In the event of designing, the overall goal was to obtain a voltage standing wave ratio (VSWR) less than 2 at 2.4 GHz signal frequency. To receive the intended results, the dimensions and design of the microstrip patch were important factors given the substrate parameters. Currently, the project is in the prototyping stage for the validation of simulation results and further optimization and development of the antenna for microwave breast cancer detection and imaging applications

Layer-By-Layer Self-Assembly of CIGS Nanoparticles and Polymers for All-Solution Processable Low-Cost, High-Efficiency Solar Cells

poster abstractThin film solar cells made from copper indium gallium selenide (CIGS) materials have shown great potentials of providing low cost, high efficiency panels viable for wide spread commercial usage. Layer-by-layer (LbL) self-assembly is a low-cost, versatile nanofilm deposition process, however introduces polymers in the nanoparticles films, which reduces charge transport thereby affecting solar cell efficiency. This research aims to study various polymer materials to replace currently used insulating polymers in LbL, such as poly(sodium-4-styrenesulfonate) (PSS) and polyethyenimine (PEI). This poster will present processes and results of CIGS nanoparticles synthesis using controlled heating of CuCl, InCl3, GaCl3, and Se in oleyamine; functionalization of the particles to disperse in organic and aqueous-based solvents for LbL; and initial outcomes of CIGS, polymers LbL film fabrication and characterization. The size distribution of synthesized nanoparticles cleaned through alternate suspension and precipitation in chloroform and ethanol shows a peak at 72 nm. Particles light absorption properties measured with ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy shows good spectrum coverage with band edge near 1100 nm. The X-ray diffraction (XRD) results of the particles confirms the composition and tetragonal chalcopyrite crystal structure of CIGS materials. Chemical-bath-deposition of cadmium sulfide (CdS) and spray-coating of zinc oxide (ZnO) films are used along with LbL absorbing film in realization of a solar cell device. The fabricated devices are tested using semiconductor characterization instrument

Low-Power ASIC Design for Multiple Integrated Sensors Applications

poster abstractThe aim of this work is to develop sensor integrated low-power chip for biomedical and other applications. Complementary metal-oxide-semiconductor (CMOS) technology in integrated circuit (IC) design has been applied to develop application specific integrated circuits (ASIC). An ASIC design that includes analog and digital sub-systems for various applications forming a system on chip (SoC) is presented. The analog sub-system drives multiple sensors, while the digital sub-system manages power, sensors, and signal output. A frequency of the pulse signals generated by the analog sub-system depends on the input voltage, which in-turn varies with sensor parameters. The frequency change of 750 MHz to 1 GHz was observed for input voltage variations of 1.2 to 2.2 V, with sensitivity of 10 mV. A separate temperature sensor included in the analog sub-system demonstrated frequency change of 830 to 440 MHz for temperature variations of ˗50°C to 100°C with resolution of 1°C. The output signal in digital sub-system is generated by counting the input pulses for each clock which has ‘on-state’ of only 3/16 seconds. This results in a significant reduction in the power consumption. This poster presents and discusses the system design and simulation results

Physical modelling of pressure flushing of sediment using lightweight materials

While designing physical hydraulic model tests to investigate the efficiency of pressure flushing, it is most likely that very fine sediments of cohesive nature are required to satisfy the relevant scaling criteria. Cohesive sediments have different physical properties than sand, and a possibility to avoid such scale effects is to use lightweight materials with a specific gravity larger than water but lower than sand as model sediment. This paper addresses this issue by presenting results from laboratory experiments mimicking pressure flushing through a bottom outlet by using different lightweight materials and sand as model sediments. The results consolidate conclusions of previous studies carried out solely with sand and show that lightweight models can be used to predict the length and volume of flushingcones. Empirical relations to predict the length and volume of flushing cones are proposed and validated against a small set of experimental data from a previous study

Paper-Based Lithium-Ion Battery

poster abstractLithium-ion batteries have a wide range of applications including present day portable consumer electronics and large-scale energy storage. Realization of these batteries in flexible, light-weight forms will further expand the usage in current and future innovative electronic devices. Lithium titanium oxide (Li4Ti5O12), lithium magnesium oxide (LiMn2O4) and lithium cobalt oxide (LiCoO2) materials have been consistently studied for application in high capacity batteries, and thus considered in the devices that are presented in the poster. Carbon nanotube (CNT) coated wood microfiber papers are used as current collectors, which provide high surface area, flexibility, and texture of paper, with low CNT utilization (10.1μg/cm2). The CNT microfiber paper is fabricated by layer-by-layer (LbL) nano-assembly of CNT over cellulose microfibers. Results from paper-based half-cell batteries show capacities of 130 mAh/g for LiMn2O4, 150 mAh/g for LiCoO2, and 158 mAh/g for Li4Ti5O12 at C/5 rate. These results are comparable with metallic electrode based cells. The fabrication of CNT microfiber paper, assembly of batteries, experimental methods, and results are presented and discussed