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关键词： embroidery   stitch structure   RFID   conductive yarn   antenna  

摘要： As the demand for low-cost rapid preparation techniques for RFID (Radio Frequency Identification) fabric tags is increasing, embroidery technologists have attempted to fabricate tag antennas. However, the effects of stitch structures on the performance of tag antennas have rarely been studied. Since the structure of an embroidered stitch is related to the embroidering process parameters and embroidery thread, this study chose a common stitch trace type to prepare two sets of UHF RFID tag antennae by changing the embroidery thread structure and stitch length, and then the electrical and gain properties of these antennas were analyzed. And again, the reading performance of the corresponding tag was evaluated. The results showed that the antennas embroidered with copper/PET wrapped yarns have higher energy transfer efficiency than those with single copper wire yarns. When the stitch length increases from 0.9 to 5 mm, the read range of the embroidered tag firstly increases and then decreases, due to the large embroidering process deviation of the tag antenna geometry, and the optimal stitch length for the read range is 1.7 mm, where the read range is 12.95 m. When the stitch length is 5 mm, the read range is minimum - 9.56 m. In summary, this study determined the embroidered thread structure and the process design of the stitch length in terms of the performance of a fabric-based embroidery antenna for an RFID tag as well as the read range.

关键词： Antennas   Repeaters   Robots   Directive antennas   Microstrip antennas   Antenna feeds   Polarization   Radio frequency identification   RFID tags   decoupling techniques   repeater   robot  

摘要： In this article we aim to increase the range of commercial passive UHF RFID technology. We propose a prototype forward-link repeater, which consists of a pair of antennas, a band pass filter, an RF power limiter and a low-noise amplifier (LNA). Initially, we focus on the design of the two antennas with inverse direction of circular polarization (CP), so that sufficient decoupling is ensured, while adhering to the following constraints: i) the input antenna is circularly polarized to maximize the gain towards the reader's antenna, ii) the output antenna is circularly polarized to improve the probability of successful tag reception, given the expected randomness in the tag's orientation, iii) the volume of the entire structure is kept small. Then, we present the achieved range improvement of the proposed repeater in two applications: a) a fixed installation, where the reader successfully identified passive RFID tags from 60m and b) by placing the repeater on top of an autonomous robot, to provide power in distant battery-less RFID tags, while the robot randomly moves inside a large area. The robotic-repeater prototype achieved remarkable performance, inventorying distant passive RFID tags, under Non-Line-Of-Sight (NLOS) conditions with the reader, exploiting the robot's mobility for fading-mitigation, combined with increased incident power from the repeater.

关键词： Epidermis   Radiofrequency identification   Antennas   Impedance   Integrated circuits   Epidermal electronics   RFID   sensor   multi-port antenna  

摘要： Wireless epidermal devices based on Radio frequency Identification (RFID) enable a contactless and non-invasive monitoring of the human body by sampling health parameters directly on the skin. To achieve multi-parametric sensing, while preserving the intrinsic simplicity and the low cost of RFID tags, a dual-chip epidermal device is here proposed. At this purpose a polarization-diversity loop antenna is exploited so that two almost independent current modes are excited. The resulting radiation patterns are both broadside, thus enabling the simultaneous gathering of two independent dataset from the same maximum distance. A 3.5 by 3.5 cm battery-less, flexible and soft prototype provides -13 dBi embedded realized gain with read distances ranging from 0.6m to 1.5m depending on the microchip sensitivity. The electromagnetic performance of the two ports remain similar even when the tag is applied onto rather in-homogeneous body regions. With reference to body temperature monitoring, the device has been experimented in both controlled and real-life environments, demonstrating the possibility of doubling the sensing capabilities of RFID epidermal devices without affecting their size and radiation performances.

关键词： Sensors   Temperature sensors   Passive RFID tags   Pins   Temperature measurement   Semiconductor device measurement   Mechanical sensors   Digital sensor   passive sensor   temperature sensor   RFID  

摘要： Benefitting from the advancement of digital electronics in the 20(th) century, sensors have also gradually evolved from analog to digital. As semiconductor components are required in digital sensors, a power supply is still needed for the sensor. To eliminate the need for a power supply a concept of passive digital sensing is proposed. Different from the semiconductor-based electrical digital sensing method, the parameter to be measured is first converted to a mechanical signal, then the mechanical signal is encoded to multiple digital bits by a passive digitizer, where each bit is identified as open or short state that is detectable by general IO ports. To demonstrate the proposed sensing concept, a passive RFID temperature sensor is implemented using a bimetallic coil as the temperature sensing unit. The 6-bit binary codes are acquired and transmitted by a passive RFID that is powered by an energy harvester. The test results show that the temperature sensor has a measurement sensitivity of 1.32 degrees C/bit and a working distance over 10 meters.

关键词： Assisted living   epidermal RFID   human tracking system   IoT   security threats  

摘要： With the growing of human security concerns globally, high demand of technology is needed for enhancing people's security. The rapid advancement in RFID technology offers an auspicious future to people with robust location tracking for a wide variety of indoor applications, ensuring safer commutes and better monitoring. It can be used to minimize the kidnapping rate predominantly in developing countries where medical professionals are threatened for ransoms. Thus, various RFID solutions have been tested in a number of human tracking systems. However, these solutions are suffered from either being vanished, used by prohibited users or getting damaged as well as systems on the limitations of interfaces, scalability, security or privacy concerns. Therefore, an extensive approach is proposed in this study to evaluate the suitability of epidermal RFID tags (implanted under the skin) in a smart indoor human tracking system. A certifiedmodel was produced that aimed to enhance humans' safety by enabling them to obtain IDs using UHF passive RFID tags with regulated frequency of 868 MHz in developing countries. This study mostly emphasized on chip and antenna essentials such as released power gain, polarization, and read distance in order to assess the efficiency of RFID tags on their appropriateness for epidermal applications in human security. The results showed that the simulated tag had a high transmission rate with a corresponding factor of gamma = 0:6, almost 1:57 dBi power gain, and a reading distance of nearly 4 meters was achieved that indicated the suitability of the tag for use in human tracking systems. Themechanism then being implemented to a smart indoor human tracking system with a user-friendlymiddleware that worked well and able to guarantee indoor human security.

关键词： Energy transfer  

关键词： Sports  

摘要： American football is a leading sport for contact-related injuries such as cervical spine injuries, some of which result from an unforeseen hit. The use of a feedback mechanism to alert an athlete of a potential hit may mitigate the risk for sport-related concussion and catastrophic injury by allowing athletes to effectively brace for an otherwise unforeseen impact. In this project, we created a proximity sensor system using radio frequency identification (RFID) technology to send haptic feedback to the wearer before a potential impact. Our pilot test consisted of three participants who wore our novel sensor system, who ran simulated routes to represent player-to-player contact. Additionally, we used simulated data from a Network Live Football (NFL) league game to further validate our contact prediction algorithm. Results show that our method can predict players' collisions with less than 14% false-alarms. Copyright © 2021, The Authors. All rights reserved.

关键词： Internet of things  

摘要： Recently, a number of articles have proposed query tree algorithms based on bit tracking to solve the multitag collision problem in radio frequency identification systems. However, these algorithms still have problems such as idle slots and redundant prefixes. In this paper, a time slot detection-based M-ary tree (Time Slot Detection based M-ary tree, TSDM) tag anticollision algorithm has been proposed. When a collision occurs, the reader sends a predetection command to detect the distribution of the m-bit ID in the 2(m) subslots;then, the time slot after predetection is processed according to the format of the frame-like. The idle time slots have been eliminate through the detection. Using a frame-like mode, only the frame start command carries parameters, and the other time slot start commands do not carry any parameters, thereby reducing the communication of each interaction. Firstly, the research status of the anticollision algorithm is summarized, and then the TSDM algorithm is explained in detail. Finally, through theoretical analysis and simulation, it is proved that the time cost of the TSDM algorithm proposed in this paper is reduced by 12.57%, the energy cost is reduced by 12.65%, and the key performance outperforms the other anticollision algorithms.