Giulia Orecchini

Inkjet Printed, Self Powered, Wireless Sensors for Environmental, Gas, and Authentication-Based Sensing

In this paper, inkjet-printed flexible sensors fabricated on paper substrates are introduced as a system-level solution for ultra-low-cost mass production of UHF Radio Frequency Identification (RFID) Tags and wireless sensor nodes in a “green” approach that could be easily extended to other microwave and wireless applications. The authors briefly touch up the state-of-the-art area of fully integrated wireless sensor modules on paper and show several active and power scavenging platforms to power on wireless sensors that could potentially set the foundation for the truly convergent wireless sensor ad hoc networks of the future.

A New Contactless Assembly Method for Paper Substrate Antennas and UHF RFID Chips

This paper deals with a low-cost method for the assembly of flexible substrate antennas and UHF RF identification silicon (Si) chips. Such a method exploits a magnetic coupling mechanism, thus not requiring for galvanic contacts between the Si chip and antenna itself. The magnetic coupling is established by a planar transformer, the primary and secondary windings of which are implemented on flexible substrate and Si chip, respectively. As a result, the Si chip can be assembled on the antenna with a mere placing and gluing process. First, the idea has been validated by theory. Electromagnetic simulations of a square heterogeneous transformer (1.0-mm side) show a maximum available power gain (MAG) of -0.4 dB at 868 MHz. In addition, the heterogeneous transformer is also quite tolerant with respect to misalignment between primary and secondary. An offset error of 150 μm reduces the MAG to - 0.5 dB. A sub-optimal matching strategy, exploiting a simple on-chip capacitor, is then developed for antennas with 50- Ω input impedances. Finally, the idea has been experimentally validated exploiting printed circuit board (PCB) prototypes. A PCB transformer (1.5-mm side) and a transformer rectifier (two-diode Dickson multiplier) have been fabricated and tested. Measurements indicates a MAG of -0.3 dB at 868 MHz for the transformer and the capability of the developed rectifier to supply a 220-kΩ load at 1.5 V with a - 2-dBm input power.

Smart Surfaces: Large Area Electronics Systems for Internet of Things Enabled by Energy Harvesting

Energy harvesting is well established as one of the prominent enabling technologies [along with radio-frequency identification (RFID), wireless power transfer, and green electronics] for the pervasive development of Internet of Things (IoT). This paper focuses on a particular, yet broad, class of systems that falls in the IoT category of large area electronics (LAE). This class is represented by “smart surfaces.” The paper, after an introductory overview about how smart surfaces are collocated in the IoT and LAE scenario, first deals with technologies and architectures involved, namely, materials, antennas, RFID systems, and chipless structures; then, some exemplifying solutions are illustrated to show the present development of these concurrent technologies in this area and to stimulate further solutions. Conclusions and future trends are then drawn.

Wearable battery-free active paper printed RFID tag with human-energy scavenger

The embodiment of wearable battery-free, active, paper printed RFID tags provided with energy scavenging capabilities is presented. In this research, extraction of electrical energy from human body movement is obtained by a piezoelectric energy scavenger powering up an active RFID tag module implemented on flexible organic substrate. The application dealt with hereafter testifies a promising approach useful for a vast variety of applications where wearable electronics is required.

Low-Power Frequency Doubler in Cellulose-Based Materials for Harmonic RFID Applications

This letter presents the design of a Schottky diode frequency doubler suitable for harmonic RFID tags. A microwave frequency doubler is implemented in a cellulose-based (paper) substrate, i.e., an ultra-low cost, recyclable and biodegradable material. The circuit exploits a distributed microstrip structure that is fabricated using a copper adhesive laminate to have low conductor losses. The measurements show a conversion loss of 13.4 dB at the output frequency of 2.08 GHz. This is achieved with an available input power of -10 dBm only. Finally a harmonic RFID experiment proves a reading range of 50 cm, obtained by transmitting 0 dBm and receiving a second harmonic of -60 dBm, i.e., well above the sensitivity of a typical microwave receiver.

“Smart Shoe”: An autonomous inkjet-printed RFID system scavenging walking energy

In this research the embodiment of wearable battery-free, active, paper printed RFID tags with energy scavenging capabilities is presented. Extraction of electrical energy from human body movement is obtained by a piezoelectric energy scavenger powering up an active RFID tag.

Battery-free RFID-enabled wireless sensors

This paper introduces the realization of batter-free RFID-enable wireless sensors by integrating conformal RFID antennas with inkjet-printed carbon nanotubes (CNT) composites in a chipless RFID fashion for gas detection. The whole module is realized by inkjet printing on a low-cost paper-based substrate and the RFID tag is designed for the European UHF RFID band. The electrical conductivity of the CNT film changes in the presence of very small quantities of gases like ammonia, methanol, ethanol, acetone and nitrogen oxide (NOx), resulting in the variation of the backscattered power level which can be easily detected by the RFID reader to realize reliable wireless toxic gas sensing. The electrical performance characterization of the inkjet-printed CNT film is also reported in the UHF band.

Review of the present technologies concurrently contributing to the implementation of the Internet of Things (IoT) paradigm: RFID, Green Electronics, WPT and Energy Harvesting

This paper summarizes the most important technologies, concurrently participating to build the technological platform needed for a realistic implementation of the Internet of Things (IoT) paradigm. At the present state of the evolution of IoT, these technologies are mostly: Radio Frequency IDentification (RFID), Green Electronics (GE), Wireless Power Transfer (WPT) and Energy Harvesting (EH). This contribution briefly explains the reason for that, and shows a collection of scientific contributions which can be seen as examples. The deep description of the proposed systems can be found in the relative referenced papers.

An RFID system with enhanced hardware-enabled authentication and anti-counterfeiting capabilities

This paper introduces a new RFID system with enhanced hardware-enabled authentication and anti-counterfeiting capabilities. The system relies on the near-field RF effects between the multiple antennas of the reader and the uniquely modified substrate of the RF certificates of authenticity. A new stand-alone, low cost reader with 5 by 5 antennas is used to accurately extract the near-field response of RF certificates of authenticity meant to complement typical RFID tags in the 5 to 6 GHz frequency range. The RF characterization of all the readers components, with an emphasis on accuracy and insertion loss introduced, has been performed for calibration purposes. The design methodology for generating RF-COA instances that yield unique RF fingerprints is outlined. Rigorous, yet preliminary, performance and robustness test results, including uniqueness among different instances, repeatability robustness for same instance, 2D to 3D projection comparison and variation in conductive material density, are reported and verify the unique features of this technology.

Crossed dipole frequency doubling RFID TAG based on paper substrate and ink-jet printing technology

A frequency doubler TAG structure realized on both plastic and conductive ink-jet printed paper is presented. It is based on the crossed dipole structure, but uses four diodes in a bridge configuration to form a balanced multiplier layout and incorporates the necessary DC path in a simple way within the structure. Measurements results are presented for both the plastic and paper structure, showing the feasibility of economic and green electronics on paper.