| 1. |
- Amin, Yasar
(författare)
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Printable Green RFID Antennas for Embedded Sensors
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the recent years, radio-frequency identification (RFID) technology has been widely integrated into modern society applications, ranging from barcode successor to retail supply chain, remote monitoring, detection and healthcare, for instance. In general, an RFID tag or transponder is composed of an antenna and an application-specific integrated circuit chip. In a passive UHF RFID system (which is the focus of presented research), the communication between the transponder tag and the reader is established by modulating the radar cross section (RCS) of the transponder tag. The need for flexible RFID tags has recently been increased enormously; particularly the RFID tags for the UHF band ensure the widest use but in the meantime face considerable challenges of cost, reliability and environmental friendliness.The multidimensional focus of the aforementioned research encompasses the production of low-cost and reliable RFID tags. The state-of-the-art fabrication methods and materials for proposed antennas are evaluated in order to surmount the hurdles for realization of flexible green electronics. Moreover, this work addresses the new rising issues interrelated to the field of economic and eco-friendly tags comprising of paper substrate. Paper substrates offer numerous advantages for manufacturing RFID tags, not only is paper extensively available, and inexpensive; it is lightweight, recyclable and can be rolled or folded into 3D configurations.The most important aspect of an RFID system's performance is the reading range. In this research several pivotal challenges for item-level tagging, are resolved by evolving novel structures of progressive meander line, quadrate bowtie and rounded corner bowtie antennas in order to maximize the reading distance with a prior selected microchip under the various constraints (such as limited antenna size, specific antenna impedance, radiation pattern requirements). This approach is rigorously evolved for the realization of innovative RFID tag antenna which has incorporated humidity sensor functionality along with calibration mechanism due to distinctiveness of its structural behavior which will be an optimal choice for future ubiquitous wireless sensor network (WSN) modules.The RFID market has grown in a two-dimensional trend, one side constitutes standalone RFID systems. On the other side, more ultramodern approach is paving its way, in which RFID needs to be integrated with broad operational array of distinct applications for performing different functions including sensors, navigation, broadcasting, and personal communication, to mention a few. Using different antennas to include all communication bands is a straightforward approach, but at the same time, it leads to increase cost, weight, more surface area for installation, and above all electromagnetic compatibility issues. The indicated predicament is solved by realization of proposed single wideband planar spirals and sinuous antennas which covers several bands from 0.8-3.0GHz. These antennas exhibit exceptional performance throughout the operational range of significance, thus paving the way for developing eco-friendly multi-module RF industrial solutions.
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| 2. |
- Feng, Yi
(författare)
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Printed RFID Humidity Sensor Tags for Flexible Smart Systems
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Radio frequency identification (RFID) and sensing are two key technologies enabling the Internet of Things (IoT). Development of RFID tags augmented with sensing capabilities (RFID sensor tags) would allow a variety of new applications, leading to a new paradigm of the IoT. Chipless RFID sensor technology offers a low-cost solution by eliminating the need of an integrated circuit (IC) chip, and is hence highly desired for many applications. On the other hand, printing technologies have revolutionized the world of electronics, enabling cost-effective manufacturing of large-area and flexible electronics. By means of printing technologies, chipless RFID sensor tags could be made flexible and lightweight at a very low cost, lending themselves to the realization of ubiquitous intelligence in the IoT era.This thesis investigated three construction methods of printable chipless RFID humidity sensor tags, with focus on the incorporation of the sensing function. In the first method, wireless sensing based on backscatter modulation was separately realized by loading an antenna with a humidity-sensing resistor. An RFID sensor tag could then be constructed by combining the wireless sensor with a chipless RFID tag. In the second method, a chipless RFID sensor tag was built up by introducing a delay line between the antenna and the resistor. Based on time-domain reflectometry (TDR), the tag encoded ID in the delay time between its structural-mode and antenna-mode scattering pulse, and performed the sensing function by modulating the amplitude of the antenna-mode pulse.In both of the above methods, a resistive-type humidity-sensing material was required. Multi-walled carbon nanotubes (MWCNTs) presented themselves as promising candidate due to their outstanding electrical, structural and mechanical properties. MWCNTs functionalized (f-MWCNTs) by acid treatment demonstrated high sensitivity and fast response to relative humidity (RH), owing to the presence of carboxylic acid groups. The f-MWCNTs also exhibited superior mechanical flexibility, as their resistance and sensitivity remained almost stable under either tensile or compressive stress. Moreover, an inkjet printing process was developed for the f-MWCNTs starting from ink formulation to device fabrication. By applying the f-MWCNTs, a flexible humidity sensor based on backscatter modulation was thereby presented. The operating frequency range of the sensor was significantly enhanced by adjusting the parasitic capacitance in the f-MWCNTs resistor. A fully-printed time-coded chipless RFID humidity sensor tag was also demonstrated. In addition, a multi-parameter sensor based on TDR was proposed.The sensor concept was verified by theoretical analysis and circuit simulation.In the third method, frequency-spectrum signature was utilized considering its advantages such as coding capacity, miniaturization, and immunity to noise. As signal collision problem is inherently challenging in chipless RFID sensor systems, short-range identification and sensing applications are believed to embody the core values of the chipless RFID sensor technology. Therefore a chipless RFID humidity sensor tag based on near-field inductive coupling was proposed. The tag was composed of two planar inductor-capacitor (LC) resonators, one for identification, and the other one for sensing. Moreover, paper was proposed to serve as humidity-sensing substrate for the sensor resonator on accounts of its porous and absorptive features.Both inkjet paper and ordinary packaging paper were studied. A commercial UV-coated packaging paper was proven to be a viable and more robust alternative to expensive inkjet paper as substrate for inkjet-printed metal conductors. The LC resonators printed on paper substrates showed excellent sensitivity and reasonable response time to humidity in terms of resonant frequency. Particularly, the resonator printed on the UV-coated packaging paper exhibited the largest sensitivity from 20% to 70% RH, demonstrating the possibilities of directly printing the sensor tag on traditional packages to realize intelligent packaging at an ultra-low cost.
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| 3. |
- Pang, Zhibo
(författare)
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Technologies and Architectures of the Internet-of-Things (IoT) for Health and Well-being
- 2013
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- The emerging technology breakthrough of the Internet-of-Things (IoT) is expected to offer promising solutions for food supply chain (FSC) and in-home healthcare (IHH), which may significantly contribute to human health and well-being. In this thesis, we have investigated the technologies and architectures of the IoT for these two applications as so-called Food-IoT and Health-IoT respectively. We intend to resolve a series of research problems about the WSN architectures, device architectures and system integration architectures. To reduce the time-to-market and risk of failure, business aspects are taken into account more than before in the early stage of technology development because the technologies and applications of IoT are both immature today.The challenges about enabling devices that we have addressed include: the WSN mobility and wide area deployment, efficient data compression in resource-limited wireless sensor devices, reliable communication protocol stack architecture, and integration of acting capacity to the low cost intelligent and interactive packaging (I2Pack). Correspondingly, the WAN-SAN coherent architecture of WSN, the RTOS-based and multiprocessor friendly stack architecture, the content-extraction based data compression algorithm, and the CDM-based I2Pack solution are proposed and demonstrated.At the system level, we have addressed the challenges about effective integration of scattered devices and technologies, including EIS and information integration architectures such as shelf-life prediction and real-time supply chain re-planning for the Food-IoT, and device and service integration architectures for the Health-IoT. Additionally, we have also addressed some challenges at the top business level, including the Value Chain Models and Value Proposition of the Food-IoT, and the cooperative ecosystem model of the Health-IoT. These findings are generic and not dependent on our proprietary technologies and devices.To be more generalized, we have demonstrated an effective research approach, the so-called Business-Technology Co-Design (BTCD), to resolve an essential challenge in nowadays research on the IoT -- the lack of alignment of basic technology and practical business requirements. We have shown its effectiveness by our design practice. It could be an instructive example of “the change of mindset” which is essential for the IoT research in the future.
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| 4. |
- Zhou, Qin, 1984-
(författare)
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Sub-Nyquist Sampling Impulse Radio UWB Receivers for the Internet-of-Things
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the era of Internet-of-Things, the demand for short range wireless links featured by low-power and low-cost, robust communication and high-precision positioning is growing rapidly. Impulse Radio Ultra-Wideband (IR-UWB) technology characterized by the transmission of sub-nanosecond pulses spanning up to several GHz band with extremely low power spectral density emerges as a promising candidate. Nevertheless, several challenges must be confronted in order to take the full advantage of IR-UWB technology. The most significant one lies in the reception of UWB signals. Traditional receiver requires Nyquist rate ADC which is overwhelmingly complex and power hungry. This dissertation proposes and investigates possible sub-Nyquist sampling techniques for IR-UWB receiver design.In the first part of this dissertation, the IR-UWB receiver based on energy detection (ED) principle is explored. A low-power ED receiver featured by flexibility and multi-mode operation is proposed. The receiver prototype for 3-5 GHz band is implemented in 90 nm CMOS. Measurement results demonstrate that 16.3 mW power consumption and -79 dBm sensitivity at 10 Mb/s data rate can be achieved. To further optimize the receiver performance, threshold optimization is suggested for the on-off-keying modulated signal, and adaptive synchronization and integration region optimization is proposed. Finally, a low complexity burst packet detection scheme is proposed, which is adaptive to the variations of noise background and link distance.In the second part of this dissertation, the IR-UWB receiver based on compressed sensing (CS) theory is investigated. Firstly, appropriate sparse basis, sensing matrix and reconstruction algorithms are suggested for the CS based IR-UWB receiver. And then, the architectural analysis of the CS receiver with focuses on the random noise processes in the CS measurement procedure is presented. At last, a novel two-path noise-reducing architecture for the CS receiver is proposed. Besides the improvement on the receiver performance, the proposed architecture also relaxes the hardware implementation of the CS random projection as well as the back-end signal reconstruction.
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