Abstract-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-ofthe-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.

Abstract-Passive ultra high-frequency radio frequency identification tags, besides item labeling, are also able to exploit capability to sense the physical state of the tagged object as well as of the surrounding environment. Here, a new family of polymer-doped tags are proposed and fully characterized for the detection of ambient humidity. A sensitive chemical species based on PEDOT:PSS is used to load a shaped slot, carved into a foldedlike patch tag. The communication and sensing capabilities of the resulting radio-sensor are investigated by means of simulation and measurements that show how to control and balance above opposite requirements by a proper deposition of the sensitive material. The device could have interesting applications in the assessment of the air quality within living and controlled rooms, in the monitoring of the conservation state of foods, in the preservation of walls, and even in the medical field, e.g., to monitor the healing of wounds.

Recent progresses in the design of wearable RFID-tag antennas stimulate the idea of passive body-centric systems, wherein the required power to drive the wearable tags is directly scavenged from the interrogation signal emitted by the reader unit. While active body-centric links have been extensively investigated, the feasibility of passive systems is still questionable, due to the poor sensitivity of the tags and due to the modest reading distances. This paper describes a systematic measurement campaign involving low-profi le wearable textile tags in the UHF RFID band. It was demonstrated that both on-body and off-body links are affordable, with a power budget fully compliant with the available technology and the safety standards. The experiments permitted identifying the most-effi cient tag placements, and proposing some quantitative and general guidelines useful to characterize and design this kind of new system.

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By carving a 'square-smile' slot profile over a folded patch, a miniaturised UHF-RFID tag is obtained, having a convenient two-step tuning mechanism (coarse and fine). This is useful to adapt the same tag to European and US frequencies and to make on-site corrections. The antenna is half the size of a credit card and can be read up to 5m when attached onto the body. The flexible and lightweight EPDM foam substrate makes the tag suited to be integrated in badges, wallets, pockets, plasters, wristbands and various garments.Introduction: Radio frequency identification (RFID) and wireless sensor systems are emerging technologies, attracting remarkable interest in security, healthcare, biomedical applications and even entertainment and social arts. Passive devices are particularly attractive for bodycentric platforms owing to their light weight, low cost and the absence of battery recharging. In particular, tags integrated into clothes, eventually hosting specific sensors, make it possible to remotely monitor human body activity [1,2]. In recent years, several on-body passive dipole and patch tags have been presented [3 -5] for the UHF (866-956 MHz) RFID frequency, but smaller layouts are however needed in some applications in order to simplify the integration with clothes or plasters. Miniaturisation of wearable passive tags generally produces a remarkable degradation of the antenna bandwidth as well as of the radiation efficiency due to the presence of the lossy human body. As a consequence, this can negatively affect the interoperability in different countries and the stability of the performances with respect to the specific body placement.Starting from previous experiments of the same authors with wearable tags in [2], this Letter proposes a new layout over a flexible and low-cost substrate with reduced external dimensions. The geometry provides a two-step tuning mechanism that permits in principle to easily adapt the same tag to any frequency inside the world-wide UHF RFID band (866-956 MHz) and even to make finer corrections for the specific placement. The antenna potentiality is here demonstrated by a parametric analysis and measurements on real prototypes.