Search Results (10)

This article reviews the recent advances in the field of batteryless near-field communication (NFC) sensors for chemical sensing and biosensing. The commercial availability of low-cost commercial NFC integrated circuits (ICs) and their massive integration in smartphones, used as readers and cloud interfaces, have aroused great interest in new batteryless NFC sensors. The fact that coil antennas are not importantly affected by the body compared with other wireless sensors based on far-field communications makes this technology suitable for future wearable point-of-care testing (PoCT) devices. This review first compares energy harvesting based on NFC to other energy-harvesting technologies. Next, some practical recommendations for designing and tuning NFC-based tags are described. Power transfer is key because in most cases, the energy harvested has to be stable for several seconds and not contaminated by undesired signals. For this reason, the effect of the dimensions of the coils and the conductivity on the wireless power transfer is thoroughly discussed. In the last part of the review, the state of the art in NFC-based chemical and biosensors is presented. NFC-based tags (or sensor tags) are mainly based on commercial or custom NFC ICs, which are used to harvest the energy from the RF field generated by the smartphone to power the electronics. Low-consumption colorimeters and potentiostats can be integrated into these NFC tags, opening the door to the integration of chemical sensors and biosensors, which can be harvested and read from a smartphone. The smartphone is also used to upload the acquired information to the cloud to facilitate the internet of medical things (IoMT) paradigm. Finally, several chipless sensors recently proposed in the literature as a low-cost alternative for chemical applications are discussed. Full article

This research is focused on the evaluation of cutting edge wear of the delimbing knife by contactless methods. Delimbing knives were tested in an experimental device constructed in our laboratory, which operates on the principle of a forest harvester head. The greatest wear of the cutting edge was manifested in knife no. 1 with a blade angle of ∢ 7°. The research was focused on the wear of delimbing knives made of DIN 58SiCr8/WNr material when changing the angular geometry of the tool and using a constant delimbing speed of 2.0 m.s⁻¹ while delimbing spruce wood of various wood diameters. The Alicona Infinite Focus device, which functions as a non-contact 3D optical device, was used to determine the amount of wear on the cutting edge of the knife. The size of cutting edge wear significantly affects chipless cutting wood, which can be observed in an increase in the cutting force during the delimbing process. The use of harvester technology in forestry is a highly topical issue today. From this point of view, it is necessary to focus on increasing the efficiency and reducing the energy consumption of the machine, which economically benefits its delimbing operation. Full article

This paper was concerned with the current level of progress towards the development of chipless radio frequency identification (RFID) sensors that are capable of sensing strain and temperature. More specifically, it was interested in the possibility that the resulting devices could be used as a passive wireless structural health monitoring (SHM) sensor technology that could be printed in situ. This work contains the development and performance characterization results for both novel strain and novel temperature sensor designs with resulting sensitivities of 9.77 MHz/%ε and 0.88 MHz/°C, respectively. Furthermore, a detailed discussion on the interrogation system required to meet the relevant aerospace sensing requirements was also discussed, and several methods were explored to enhance the multi-sensor support capabilities of this technology. Full article

Selective laser melting is a frequently used, powder bed fusion additive manufacturing technology for producing metallic parts. However, appropriate surface quality cannot be achieved, so post-processing is often necessary. Subsequent machining of surfaces serves multiple objectives such as improvement of dimensional accuracy, changing surface roughness and modification of the residual stress state for higher surface hardness. Beyond its several advantageous properties, Ti6Al4V material has, as its weaknesses, low tribological behavior and wear resistance. Sliding friction burnishing is a conventional chipless and coolant-free environmentally conscious technology for surface modification that is appropriate for simultaneously decreasing surface roughness and increasing surface hardness. Until now, there has been a research gap regarding the diamond burnishing of selective laser melted Ti6Al4V parts. In this study, we investigated how the surface roughness of selective laser melted parts can be modified via sliding friction burnishing. 2D and 3D characteristics of surface roughness were measured by a chromatic roughness measuring device. Indices of surface roughness improvement were defined and studied as a function of selective laser melting parameters. Optimal manufacturing parameters of laser power—P = 280 W and scanning speed u = 1200 mm/s—for effective surface improvement via burnishing are proposed. Full article

Internet of Things (IoT) has been developing to become a free exchange of useful information between multiple real-world devices. Already spread all over the world in the most varied forms and applications, IoT devices need to overcome a series of challenges to respond to the new requirements and demands. The main focus of this manuscript is to establish good practices for the design of IoT devices (i.e., smart devices) with a focus on two main design challenges: power and connectivity. It groups IoT devices in passive, semi-passive, and active, giving details on multiple research topics. Backscatter communication, Wireless Power Transfer (WPT), Energy Harvesting (EH), chipless devices, Simultaneous Wireless Information and Power Transfer (SWIPT), and Wake-Up Radio (WUR) are some examples of the technologies that will be explored in this work. Full article

In this work, two fully-textile wearable devices, to be used as chipless identification tags in identification and tracking applications are presented. For the fabrication of the fully-textile tags, a layer of fleece was used as a substrate, while an adhesive non-woven conductive fabric was employed for the conductive parts. To allow radio-frequency identification of these chipless tags, two alternative techniques were used. One relies on associating a binary code with the resonance frequency of resonant devices: the presence/absence of the resonance peaks in the transmission scattering parameter, $|S_{21}|$ , of a set of resonators is used to encode a string of bits. The second technique for accomplishing radio-frequency identification of the chipless tags resorts to a frequency-shift coding technique, which is implemented by modifying the configuration of a hairpin resonator. The obtained numerical and experimental results confirm the suitability of the proposed strategies for obtaining entirely-textile, wearable chipless tags for identification and tracking purposes, which can be particularly useful, especially in the industrial sector. In this field, in fact, the proposed solutions would guarantee a seamless integration with clothes and would facilitate the user’s interaction with the IoT infrastructure. In this regard, one of the envisaged application scenarios related to the tracking of hides in the leather industry is also presented. Full article

In this paper, a frequency-signature Radio-Frequency Identification (RFID) chipless tag for wearable applications is presented. The results achieved for a fully-textile solution guaranteeing a seamless integration in clothes are reported and discussed. The proposed tag consists of two planar monopole antennas and a 50 Ω microstrip line loaded with multiple resonators. In order to achieve a compact size, the resonators are slotted on the ground plane of the microstrip line. As for the antennas, the same geometry was exploited for both the TX and the RX tag antenna. In particular, it consists of a proximity fed planar monopole on a ground plane. The selected geometry guarantees easy integration with the multi-resonator structure. Numerical and experimental data referring to a 2-bit implementation are presented and discussed. For fabricating all the prototypes, a layer of pile was used as a substrate, while an adhesive non-woven conductive fabric was exploited for the fabrication of the conductive parts. Experimental tests demonstrate that although the performance of the final device strongly depends on the properties of the used materials and on the imperfections of the fabrication process, the proposed frequency-signature RFID chipless tag is suitable for wearable applications, such as anti-counterfeiting systems and laundry labels. Full article

This work presents a novel approach for improving the detection capabilities of a chipless Radio Frequency Identification (RFID) system based on quantile regression. The main drawback of chipless RFID systems is the limited response of the tags due to the low-quality factor of the resonators, used to encode the information in the tag. The detection becomes very challenging especially for real-time data when noise is present. This work proposes the use of quantile regression to enhance the system performance. A chipless RFID system prototype has been fabricated (as a proof of concept) and experimentally assessed. The obtained results are quite satisfactory in the potentialities of the proposed methodology. Full article

A novel, chipless, Radio Frequency Identification (RFID) sensor is proposed for monitoring angular rotation. The rotation state is recovered by collecting the cross polar response of a tag, based on a periodic surface composed of a set of dipoles. The encoding mechanism allows the sensor to be very robust, even if it is applied on metallic objects, or in an environment with strong multipath. The proposed sensor does not require a large operational bandwidth. Instead, only a small set of reading frequencies are required. The number of reading frequencies required is dependent on the number of the employed dipoles. It is demonstrated that the rotation state of an object can be monitored within a span of 180 degrees, with up to a three-degree resolution, by employing a chipless RFID sensor comprising of four dipoles. The far field reading scheme and the absence of any electronics device allow the sensor to be employed in harsh environments. Full article

This article reports the first results of a Nafion^®-based, solid state, non-volatile, electronically reconfigurable Radio Frequency (RF)-switch integrated to a co-planar waveguide transmission line (CPW) in shunt mode, on a flexible paper substrate. The switch is based on a metal–insulator–metal structure formed respectively using Silver–Nafion–aluminum switching layers. The presented device is fully passive and shows good performance till 3 GHz, with an insertion loss less than 3 dB in the RF-on state and isolation greater than 15 dB in the RF-off state. Low-power direct current pulses in the range 10 V/0.5 mA and −20 V/0.15 A are used to operate the switch. The device was fabricated in an ambient laboratory condition, without the use of any clean room facilities. A brief discussion of the results and potential application of this concept in a re-configurable chipless RFID tag is also given in this article. This study is a proof of concept of fabrication of electronically re-configurable and disposable RF-electronic switches on low cost and flexible substrates, using a process feasible for mass production. Full article