Sara Amendola

RFID Technology for IoT-Based Personal Healthcare in Smart Spaces

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 users 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 body centric systems and for gathering information (temperature, humidity, and other gases) about the users 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.

Backscattering Neural Tags for Wireless Brain-Machine Interface Systems

Brain-machine interface (BMI) technology has tremendous potential to revolutionize healthcare by greatly improving the quality of life of millions of people suffering from a wide variety of neurological conditions. Radio-frequency identification (RFID)-inspired backscattering is a promising approach for wireless powering of miniature neural sensors required in BMI interfaces. We analyze the functionality of millimeter-size loop antennas in the wireless powering of miniature cortical implants through measurements in a human head equivalent liquid phantom and in the head of a postmortem pig. For the first time, we present the design and measurement of a miniature 1×1×1 mm3 backscattering device based on a cubic loop connected with an RFID integrated circuit (IC). Our measurement results show that this very small loop receives sufficient electromagnetic power to activate the IC when the device is implanted in a pigs head. This demonstrates the feasibility of extremely small implant antennas in challenging wireless biomedical systems.

Epidermal RFID passive sensor for body temperature measurements

Real-time and continuous wireless measurement of human body temperature could enable a better control of many pathologies such as the wounds infection after surgery and the evolution of epidemics involving fever rush, as well as the monitor of athletic activities. This paper describes an RFID passive UHF epidermal sensor suitable to be directly attached onto the human skin by means of a bio-compatible transpiring Poli(ε-caprolacton) (PCL) membrane. The antenna elements provide a broad matching band and even a post-fabrication tuning mechanism to better manage the specific placement over the body. The temperature is directly measured by the EM4325 microchip, also providing RFID communication capabilities. The epidermal sensor, that can be read up to 35 cm in case of 0.5 W EIRP emitted by the reader, has been moreover thermally calibrated versus a thermocouple and then applied to the measurement of human body temperature in both static and dynamic conditions with an accuracy of about 0.25°C with respect to reference measurements.

Performance of Epidermal RFID Dual-loop Tag and On-Skin Retuning

Originally introduced by the material science community, the epidermal electronics is now collecting interest also among antenna engineers for the potentiality to achieve thin and flexible sensing transponders that are suitable to application over the epidermis. Unlike conventional wearable antennas, which are generally decoupled by the lossy human body by means of spacers or shielding sheets, epidermal tags need to be placed at a very close touch with the skin thus providing poor communication capabilities. This paper investigates, by means of a detailed numerical and experimental study, the performance of an epidermal dual-loop tag for UHF radiofrequency identification (RFID) depending on the specific placement over different parts of the human body and for a variety of volunteers. An on-body tuning mechanism is also introduced and demonstrated in real applications at the purpose to improve the tag response and hence to enable the use of a same tag layout for all the UHF-RFID bands and for several placement loci.

Design, Calibration and Experimentation of an Epidermal RFID Sensor for Remote Temperature Monitoring

An epidermal radiofrequency identification technology (RFID) sensor consists of a flexible antenna provided with a radiofrequency identification and sensing microchip directly stuck over the human skin by means of a sub-millimeter bio-compatible membrane. A compact-size epidermal RFID thermometer is here proposed and extensively experimented concerning its electromagnetic and thermal performance in case of battery-less and battery-assisted configurations. The antenna element embeds a mechanism for a post-manufacturing frequency retuning in order to adapt its response to the specific placement over the body. When attached over the skin, the sensor is readable from up to 0.7 m in battery-less mode and 2.3 m in battery-assisted mode. A calibration procedure improved the accuracy of the IC sensor down to 0.18 °C. The time constant evaluated by the first-order response of the IC to impulse heating (photo-flash) resulted in 4.3 s. The epidermal wireless thermometer was experimented in both supervised applications (manual reading) and in un-supervised architectures where users were continuously monitored by a fixed remote antenna or during the crossing of a surveillance gate. In all the considered cases, the reliability of the interrogation link was experimentally quantified and resulted robust for health monitoring applications in clinical and domestic settings and even for the automatic detection of anomalous temperature peaks of people walking within airports and at country border crossing.

Movement Detection of Human Body Segments: Passive radio-frequency identification and machine-learning technologies.

Movement detection of human body segments is a fertile research topic in human-computer interaction, as well as in medical and entertainment applications. In spite of the fact that most of the current methods to track motion are based on optoelectronic systems and wearable inertial sensors, promising solutions could spring from the application of passive radio-frequency identification (RFID) technology. When the human bodys limbs move within an electromagnetic field radiated by an interrogating antenna, a movement-dependent modulation of the backscattered field is sensed by the remote receiver. The collected signals, properly conditioned by wearable electromagnetic markers (tags), may therefore carry intrinsic information about human motion. This article investigates the potentiality of the synergy between electromagnetics and machine-learning technologies to classify gestures of arms and legs by using only passive and sensorless transponders. The electromagnetic signals, backscattered from the tags during gestures, are collected by a fixed reader antenna and processed by the support vector machine (SVM) algorithm to recognize periodic limb movements and classify more complex random motion patterns. Experimental sessions demonstrated a classification accuracy higher than 80-90%, which is comparable to more complex systems involving active wearable transceivers. The results further indicate that the achievable bit rate is 48 b/min, suggesting that the platform could be used to input coded controls to a gesture-oriented user interface.

Optimal Performance of Epidermal Antennas for UHF Radiofrequency Identification and Sensing

Skin-mounted electronics is the new frontier for unobtrusive body-centric monitoring systems. In designing the wireless devices to be placed in direct contact with the human skin, the presence of the lossy body cannot be ignored because of strong electromagnetic interactions. In this paper, the performance of epidermal antennas, for application to radio frequency identification (RFID) links in the UHF band, was investigated by means of numerical simulations and laboratory tests on fabricated prototypes. The analysis demonstrates the existence of an optimal size of the antennas (from 3 to 6 cm for loops and from 6 to 15 cm for dipoles) and of upper bounds in the achievable radiation gain (less than −10 dB in the case of 0.5 mm thick application substrates) as a consequence of the balance between the two opposing mechanisms of radiation and loss. This behavior, which is controlled by the hosting medium, does not depend on the antenna shape, even if the loop layout permits considerably minimizing the device size. Even the conductivity of the antenna trace plays only a second-order role; low-cost inkjet printable paints with conductivity higher than

Thermal characterization of epidermal RFID sensor for skin temperature measurements

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RFID-Based Multi-level Sensing Network for Industrial Internet of Things

S/m are suitable to provide radiation performance comparable with the performance of copper-made antennas. Starting from the investigation of the above cited physical phenomena, including the effect of common classes of suitable substrate membranes, guidelines are finally derived for the optimal design of real RFID epidermal antennas.

Reliability of a re-usable wireless Epidermal temperature sensor in real conditions

The measurement of skin temperature is essential in both thermo-physiological and clinical applications as well as for sport medicine. The jointed development of Epidermal Electronics systems and UHF RFID technology for skin applications originates novel solution for the wireless passive sensing of body temperature. In this paper the thermal characterization of a small size (2.5cm × 5cm) epidermal RFID thermometer is addressed. After unifom recalibration, the accuracy of the RFID sensors results below 0.25°C while the response time is equal to 4.3 sec, thus enabling the reliable monitoring of surface temperature under both static and dynamic conditions.