The current evolution of the traditional medical model toward the participatory medicine can be boosted by the Internet of Things (IoT) paradigm involving sensors (environmental, wearable, and implanted) spread inside domestic environments with the purpose to monitor the user’s health and activate remote assistance. RF identification (RFID) technology is now mature to provide part of the IoT physical layer for the personal healthcare in smart environments through low-cost, energy-autonomous, and disposable sensors. It is here presented a survey on the state-of-the-art of RFID for application to bodycentric systems and for gathering information (temperature, humidity, and other gases) about the user’s living environment. Many available options are described up to the application level with some examples of RFID systems able to collect and process multichannel data about the human behavior in compliance with the power exposure and sanitary regulations. Open challenges and possible new research trends are finally discussed.

RFID Technology for IoT-Based Personal Healthcare in Smart Spaces

This paper will review the evolution of wearable textile antennas over the last couple of decades. Particular emphasis will be given to the process of embroidery. This technique is advantageous for the following reasons: (i) bespoke or mass produced designs can be manufactured using digitized embroidery machines; (ii) glue is not required and (iii) the designs are aesthetic and are integrated into clothing rather than being attached to it. The embroidery technique will be compared to alternative manufacturing processes. The challenges facing the industrial and public acceptance of this technology will be assessed. Hence, the key opportunities will be highlighted.

https://www.mdpi.com/2079-9292/3/2/314/pdf?view=inline

Embroidery and related manufacturing techniques for wearable antennas: Challenges and opportunities

It was recently reported that thermally malleable polymers with bond exchange reactions (BERs) can rearrange their microscopic network topology without impairing the network integrity. Besides, two pieces of polymers were shown to be able to weld together upon heating without introducing additional monomers or chemicals on the interface, enabling thermoforming, self-healing, and reprocessing of the polymer, which has drawn significant interest in the study of this type of polymers. This new breakthrough also opens an avenue to recycle thermoset polymers that traditionally are very difficult to recycle. This paper experimentally studies the reprocessing and recycling ability of a thermoset polymer (an epoxy thermosetting network) with exchangeable bonds in a pulverous state. Due to the large surface area and small size of polymer particles, their handling, transportation, and storage can offer convenience in comparison with traditional polymer scrap in bulk form, which can advance their immediate industrial applications in thermoset recycling, structure rehabilitations and component rework. A detailed investigation was performed to study the effect of reprocessing conditions (such as time and pressure) on the material mechanical performance. The reprocessing routine was also repeated multiple times (representing multiple generations of recycling) to manufacture complex objects and to join two separate bulk polymers.

/pdf/reprocessing-and-recycling-of-thermosetting-polymers-based-5fccevodtt.pdf

Reprocessing and recycling of thermosetting polymers based on bond exchange reactions

UHF passive radio-frequency identification technology is rapidly evolving from simple labeling of things to wireless pervasive sensing. A remarkable number of scientific papers demonstrate that objects in principle can have their physical properties be remotely tracked and monitored all along their life cycle. The key background is a new paradigm of antenna design that merges together the conventional communication issues with more-specific requirements about sensitivity to time-varying boundary conditions. This paper presents a unified review of the state of the art of the tag-as-sensor problem. Particular care is taken to formalize the measurement indicators and the communication and sensing tradeoff, with the purpose to provide a first knowledge base for facing a large variety of emerging sensing applications.

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Passive UHF RFID antennas for sensing applications: Principles, methods, and classifcations

In this paper, an RF identification sensor system is developed. It comprises passive sensors and an ultra-wideband (UWB) reader. The sensors are based on time-coded chipless tags. They consist of an UWB antenna connected to a delay line that is, in turn, loaded with a resistive temperature sensor. This sensor modulates the amplitude of the backscattered signals as a function of the temperature. The sensor tags are identified by changing the length of the delay line. In this paper, the operation principle and design of time-coded tags is presented and the integration of sensors in these tags is addressed. In addition, two measurement techniques are compared to implement the UWB reader. The first one is based on frequency sweeping and uses a vector network analyzer. The second one is based on a low-cost UWB radar. A full characterization of the sensor system is provided.

Passive Wireless Temperature Sensor Based on Time-Coded UWB Chipless RFID Tags

A small and flexible metal mountable UHF RFID tag antenna, utilizing a high-permittivity substrate material is presented. The tag is composed of a small single-layer T-matched dipole antenna, on a flexible ceramic (BaTiO3) polymer (polydimethylsiloxane) composite substrate, with a thickness of 1.5 mm. The flexibility of the substrate allows it to be mounted on flat and cylindrical metallic surfaces. The performance of the developed tag is evaluated through simulations and measurements on both flat and cylindrical metallic platforms of various sizes. The results show that the tag achieves state-of-the-art size-performance ratio while meeting the key requirements of an affordable RFID tag with a simple and flexible structure.

Small and Flexible Metal Mountable Passive UHF RFID Tag on High-Dielectric Polymer-Ceramic Composite Substrate

The design of a novel chipless radio frequency identification (RFID) tag, which is inkjet-printed on a polyimide substrate, is presented. It is shown that a silver nanoparticles-based ink can be combined with a resistive organic ink to create a tag having a “near-transparent” configuration. By adding some transparent elements, we obtain various electromagnetic responses for tags visually similar. The tag is composed of three dual-rhombic loop resonators for a total size of 7 × 4 cm2. It operates within the ultrawideband frequency range of 3-6 GHz. The resistive properties of the organic ink enable the implementation of a novel coding technique based on amplitude shift keying. Simulation and measurement results validate the concept and the novel coding technique.

/pdf/a-novel-near-transparent-ask-reconfigurable-inkjet-printed-3d3bt13iiy.pdf

A Novel Near-Transparent ASK-Reconfigurable Inkjet-Printed Chipless RFID Tag

A possible method of utilizing paraffin wax as a substrate material in developing a threshold heat sensing radio frequency identification (RFID) tag is discussed. A small narrowband passive UHF RFID tag is made on top of a multilayer substrate. Paraffin wax acts as the main heat sensitive layer of the substrate. The properties and characteristics of the paraffin layer change due to heat. The narrowband tag on top of the substrate is designed to be sensitive enough to detect any structural and physical changes of the substrate material. The changes in the properties of the substrate material will cause a shift in the operating frequency of the tag. This frequency shift will reduce the performance of the narrowband RFID sensor tag. The change in the properties of paraffin wax after being exposed to heat is irreversible under normal conditions and therefore, the proposed RFID tag can be referred to as a threshold heat sensing device. Such a low-cost solution can be useful in detecting heat exposures in various supply chains and transportation mishandling of heat sensitive items.

Passive UHF RFID Tag for Heat Sensing Applications

This paper presents the design of a sewed chipless RFID tag and sensor, on a fabric for wearable applications. The proposed design is based on three sewn scatterers on cotton textile. The tag is realized using a computer-aided sewing machine and electro-thread plated with silver. The simulation and frequency-domain measurement results validate the design from 3 to 6 GHz. The tag's static backscattered response can be identified in free space and on the human body. Some preliminary results from a sewn stretchable sensor are also given to demonstrate the potential for biomedical applications. Finally, we discuss the main challenges concerning the practical implementation of this technology.

Design and realization of stretchable sewn chipless RFID tags and sensors for wearable applications

Purpose – The purpose of this paper is to develop a novel totally passive, wireless temperature sensor tag based on ultra high-frequency (UHF) radio frequency identification (RFID) technology. The temperature-sensing functionality is enabled by using distilled water embedded in the tag antenna substrate. The novel sensor tag is designed to provide wireless temperature readings comparable to a commercial thermocouple thermometer even in environments with high levels of interference, such as reflections. The structure of the novel sensor tag is aimed to increase its usability by minimizing user-created errors and to simplify the measurement procedure. Design/methodology/approach – The sensor tag is based on a dual port sensing concept in which two ports are used to obtain sensor readings. By utilizing two ports instead of one, the effects of environmental interference, tag-reader antenna orientation and distance can be effectively minimized. Two alternative methods of acquiring the sensor reading from the o...

A. A. Babar

Papers

Small and Flexible Metal Mountable Passive UHF RFID Tag on High-Dielectric Polymer-Ceramic Composite Substrate

A Novel Near-Transparent ASK-Reconfigurable Inkjet-Printed Chipless RFID Tag

Passive UHF RFID Tag for Heat Sensing Applications

Design and realization of stretchable sewn chipless RFID tags and sensors for wearable applications

Dual port temperature sensor tag for passive UHF RFID systems