Performance comparison of inkjet and thermal transfer printed passive ultra-high-frequency radio-frequency identification tags

The authors compare the maximum read range of passive ultra-high-frequency radio-frequency identification tags that have been produced using different metal printing techniques, specifically inkjet printing and thermal transfer printing (TTP). They used the same substrate (THERMLfilm), antenna designs and electronic circuitry in their comparison so as to isolate the effect of the metal printing. Owing to the high metal conductivity, the thermal transfer printed tags printed with copper (Cu) film performed as well or better than the inkjet printed tags printed with silver ink, even when they changed the inkjet printed tags to a Kapton substrate that is better suited to inkjet printing. The aluminium (Al) thermal transfer printed tags had up to 33% less read range than Cu thermal transfer printed tags. TTP needs no sintering, and provides an attractive alternative low-cost fabrication method. Characterisation of the printed traces by both methods reveals that the printing techniques achieve similar surface roughness. The achieved conductivities for TTP on THERMLfilm were better than for inkjet. The best measured read range for TTP was 10.6 m. Across the different tag designs, the measured read ranges were 15-60% (1-10%) better for thermal printing, compared with inkjet printing on THERMLfilm (Kapton)

Analysis of Current State of The Art of RFID IC Chips

Radio Frequency Identification (RFID) is a constantly developing technology particularly in the ultra-high-frequency (UHF) band for its long operating range, power efficiency, and maintenance-free characteristics. It has been successfully developed for many applications already, that includes identification, sensing, tracking, monitoring, etc. In terms of tag, the integrated circuit (IC) or chip play an essential part in the functionality of the tag, where logical information is programmed into. Nowadays, the chips come in a variety of memory options, sensitivity, supported protocols, with an optional battery-assisted mode, additional commands, and features. There are various methods that are followed to fabricate RFID tags, i.e. inkjet-printing, painting, 3D printing, etching, etc. On the way of completion of these procedures, some of the methods involve the use of chemicals, producing waste, which is unfavorable in respect of the cost, and as well as the environment. In addition, the substrate impacts tag’s performance. If the tag is going to be attached for instance, on a metal surface the radiation properties of the tag antenna would experience changes, as the electromagnetic waves will reflect on the metal surface, which will basically degrade tag’s performance. Maintaining multiple applications on a single chip has become common to a certain extent. It requires additional power than usual, which is an issue for passive tags. In order to overcome this hurdle, energy harvesting system is required, which is going to suffice the need for a power source. In this paper, the functionalities and applications of the RFID chips have been reviewed and some suggestions have been proposed on how RFID can be commercially manufactured, in terms of fabrication methods, supplying enough power for applications, and ensuring security of the tagged object

Design and Development of Efficient and Conformal Printed Antennas for Wireless Sensing and Wearable Applications

Future wireless technologies would require flexibility from electronics that will enable the electronic components to adapt according to the everyday use environment. Flexible electronics has been used in many wireless sensing and wearable applications. One of the fastest growing wireless technologies of this decade is Radio Frequency Identification (RFID) which is an automatic identification technology that uses electromagnetic interaction to identify, sense and track people or objects with transponders known as tags. RFID is rapidly replacing the bar code technology in supply chain applications and huge amount of tags are needed to be produced in order to meet the needs of this application. The production method and material selection are few of the key parameters which are under study for the cost-effective and efficient fabrication of RFID tags and wearable antennas. The latest manufacturing technologies such as inkjet, thermal and three dimensional (3D) printing have shown good potential in improving the fabrication process, however they need to be optimized and explored further to get the best possible results.This thesis reports the use of novel manufacturing methods for the development of passive Ultra High Frequency (UHF) RFID tags and wearable antennas on versatile substrates. Commercially available as well as 3D printed flexible substrates along with different conductive inks/pastes are used for the improvement in the fabrication process. The first part of the research compares inkjet and thermal printing for the RFID fabrication in detail and suggests suitable optimizing parameters for the materials under study. The second part of the research focuses on 3D printing of the substrates and then utilizing brush painting, 3D dispensing and embroidery process to improve the overall fabrication. In addition, the fabricated antennas are tested for humidity, bending and stretching for specific applications.The results indicate that the approach and methodologies used have great potential in improving the fabrication of RFID tags and antennas. The fabricated tags show excellent results and achieve the required performance for modern RFID applications such as supply chain, wearable biomedical sensing and environment monitoring. This detailed study will be very helpful to find out appropriate materials for fabricating wireless components with the best possible results, i.e. easy to fabricate, reliable and better wireless performance, for future applications such as Internet of Things (IoT) and smart RFID packaging

Development of Sensor Integrated and Inkjet-Printed Tag Antennas for Passive UHF RFID Systems

Radio frequency identification (RFID) is a form of automated identification technology that is nowadays widely used to replace bar codes in asset tracking and management. Looking ahead to the future, our lives will be surrounded by small, embedded and wireless electronic devices that provide information about everything for everybody through pervasive computing. At the core of this vision lie two key concepts of ubiquitous sensing and the Internet of Things. RFID technology is seen as one of the most prominent technologies of today for the implementation of these future concepts. Ubiquitous sensing describes a situation, where small embedded sensors monitoring various environmental parameters are found everywhere. The second concept, the Internet of Things, requires that all objects, even the most insignificant everyday items, surrounding us should encompass computing and communication capabilities of some sort. In its simplest form, such computing could be a transponder that allows the unique identification and tracking of the item. Together these future concepts could truly revolutionize our lives by delivering significantly more information from our living environment. The objectives of this thesis are twofold. Firstly, passive ultra-high frequency (UHF) RFID technology is utilized to develop low cost, completely passive, wireless sensor devices for ubiquitous sensing applications. Secondly, inkjet-printed passive UHF RFID tag antennas are developed and optimization techniques are presented to lower the cost of such tag antenna implementations. The latter objective aims to facilitate the advancement of the Internet of Things by enabling tag antennas to be directly printed on or in to various objects. As a result of the research work presented in this thesis, three different passive UHF RFID based sensor tags were developed. Two of these designs monitor temperature and one is developed for relative humidity measurements. For the first time, the applicability and accuracy of such passive sensor tags was demonstrated. The results show that UHF RFID sensor tags have potential to be utilized as low cost sensor devices in ubiquitous applications. In addition, this thesis presents methods to lower the costs of inkjet-printed tag antennas. A technique was developed to reduce the ink consumption significantly to produce high performance tag antennas. Moreover, a special type of tag antenna design consisting of very narrow lines was developed. Finally, novel electronic materials were used as tag antenna substrate materials for inkjet-printed tag antennas. The use of a high permittivity ceramic-polymer composite, wood veneer, paper and cardboard were demonstrated. In each case, it was shown that inkjet-printing is a feasible form of fabrication on such materials, producing passive UHF RFID tags with long read ranges. This shows that tag antennas can be inkjet-printed directly on to various items to advance the realization of the Internet of Things

Novel Manufacturing Methods and Materials for UHF RFID Tags in Identification and Sensing Applications

The continuously increasing amount of radio frequency identification tags needed in our daily lives, not forgetting the broadly widening concept of the Internet of Things, sets high demands on the tag materials selection and manufacturing processes. The huge amount of needed tags requires environmentally sustainable material selection together with the requirement of very low cost. In addition, the manufacturing capacity needs to be very high, hence high-volume capable production methods are needed. In addition to identification applications, also sensing applications established with radio frequency identification tags are of great interest in many application fields.This thesis reports the possibilities of radio frequency identification tags manufactured on eco-friendly substrate materials using conductive inks and photonic sintering. The used manufacturing methods use raw materials efficiently. Especially brush-painting together with photonic sintering is capable for low-cost high-volume manufacturing. In addition, the possibilities of radio frequency identification tags for humidity sensing applications are studied.The results of this thesis confirmed that the materials and processes studied in this thesis are suitable for environmentally friendly low-cost radio frequency identification tag manufacturing. Especially brush-painting of regular screen printing conductive inks, both silver and copper oxide ink, on wood and cardboard substrates combined with photonic sintering confirmed to be a very good choice for the application area focused in this thesis. Furthermore, especially the use of screen printable copper oxide ink for identification applications is a very low-cost possibility. The results showed that humidity sensing with passive ultra-high frequency radio frequency identification tags, which were manufactured with regular screen printing silver ink on wood substrate without any coating on the tag, is a very promising approach