1,720,969 research outputs found
Electromagnetic Modeling of Self-Tuning RFID Sensor Antennas in Linear and Nonlinear Regimes
No full textMultistate chips for an UHF radio frequency identification ensure self-compensation of the variations in antenna impedance. This self-tuning capability can provide a digital information about the change in local boundary conditions within the vicinity of the tag. This feature can be exploited further for low-cost wireless sensing applications. An electromagnetic model of the tag in linear and nonlinear regimes allows prediction of analog and digital responses of the device depending on the boundary conditions that cause the variation of the antenna impedance and/or gain. In addition, the model provides estimation of the degradation in communication performance of the tag due to imperfect retuning of the chip impedance. The theoretical findings of the model are verified in sensing applications using a reference self-tuning tag. Sensing measurements of liquid compounds in linear regime and of the water-filling level of a box in nonlinear regime are demonstrated as a practical application of the proposed mathematical model
Epidermal radio-sensors for wireless detection of physiological parameters and sense augmentation
No full textHuman skin acts as the largest interface between the human body and the external environment, continuously interrogated by the central nervous system. The skin converts data flows from the inside to the outer environment and vice versa. Such interaction can be boosted by epidermal radio-sensors providing portions of a second skin suitable to capture and transmit physiologic parameters to environmental nodes as well to measure physical features of objects, thus restoring or augmenting the human senses. This contribution resumes epidermal antennas for application to the above two kinds of interactions for the measurements of temperature and breath and for the augmentation of the object perception
Graphene oxide-based radiofrequency identification wearable sensor for breath monitoring
No full textThe monitoring of the breathing dynamic characteristics, including the presence of biomarkers in exhaled breath, is of growing interest in non-invasive diagnosis of diseases. The authors describe a wearable radiofrequency identification device hosting a flexible antenna suitable for integration into a facemask and a sensor made of graphene oxide sensitive to the humidity variations. The resulting sensor tag was characterised in reference conditions while its communication performance was estimated by electromagnetic simulations as well as measurements over a simplified model of the human head. Finally, the whole system was tested on a volunteer and was experimentally demonstrated to be capable of detecting the inhalation/ exhalation cycles and abnormal patterns of respiration like the apnea by measuring the changes in graphene oxide resistance
Development of a new class of on-skin radio-sensors boosted by thin polymer-based batteries
Get PDFConductive polymers are currently collecting interest for the development of low-profile eco-friendly and biocompatible non-metallic batteries capable of providing a local power source for the next-generation flexible body-integrated electronics. In this contribution, we demonstrate the feasibility of an organic ultrathin and multilayered polymer-based battery integrating a radiofrequency identification (RFID) tag antenna by means of an electromagnetic characterization in UHF band of the polymeric films. The optimally modeling of the battery plus the antenna aimed to develop a new class of shape-conformable radio-sensors suitable to adhere to the skin as a tattoo as well as a plaster. A prototype of the device was manufactured and its communication performances were characterized through the measurement of the realized gain of the tag attached directly onto a volunteer's skin
Wireless Monitoring of Breath by means of a Graphene Oxide-based Radiofrequency Identification Wearable Sensor
No full textThe monitoring of the breathing dynamic charac- teristics, including the presence of biomarkers in exhaled breath, is of growing interest in noninvasive diagnosis of diseases. We describe a wearable radiofrequency identification (RFID) device hosting a flexible antenna suitable for integration into a facemask and a sensor made of graphene oxide sensitive to the humidity variations. The so obtained wearable wireless sensor was characterized in reference conditions and was then experimentally demonstrated to be capable of detecting the inhalation/exhalation cycles and abnormal patterns of respiration like the apnea by measuring the changes in graphene oxide resistance
Design and Experimentation of a Batteryless On-Skin RFID Graphene-Oxide Sensor for the Monitoring and Discrimination of Breath Anomalies
No full textReal-time and comfortable monitoring of the human breathing could allow identifying anomalies in the rhythm and waveform to be correlated with several pathologic disorders of respiratory and cardiovascular systems. A wireless sensor based on a flexible Kapton substrate, suitable to be stuck over the face skin like a plaster and provided with a graphene-oxide (GO) electrode, is here proposed for application to the monitoring of the moisture emitted during inhalations and exhalations. The GO-based electrode increases its dc resistance when exposed to humidity with a sensitivity of 60Ω/RH. The device is compatible with the radiofrequency identification (RFID) standard in the UHF band. When used in battery-less mode, it can be read up to 60 cm. The RFID sensor has been successfully experimented in a measurement campaign involving 10 volunteers asked to reproduce a set of predefined normal and pathological breaths. The resulting resistance traces permit to well clusterize the breath patterns with respect to the respiration rate (extracted by a fast Fourier transform) and to the average peak variation of the sensor's resistance with an accuracy close to 90%
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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