Passive RFID Chip Research Articles

The usage of RFID robots in logistics process management

The aim of this post is to point out the use of RFID robots in the management of logistics processes. RFID technology is defined first. RFID technology represents identification using radio frequency waves. The principle is to store the necessary data in radio frequency memory chips and then repeatedly read or write the data using a reader. We divide RFID chips into active and passive. Active RFID chips use energy from a battery, while passive RFID chips are a technology without an internal power source. Passive RFID is the most common form of RFID in warehouses, using which inventory is taken using RFID robots or hand-held RFID readers. Nowadays, many RFID robots from different manufacturers are available on the market. When choosing, I must consider where we want to use the RFID robot and choose the one that suits us based on its specific characteristics. The RFID robot is a mobile and autonomous RFID system that performs an inventory of the given space based on our initial setup. The RFID robot locates each item in 2 dimensions (x and y). Most robots can move in all directions because they can rotate without shifting. The accuracy of the inventory using the RFID robot ranges from 95-99%, while the accuracy of the inventory performed by employees using handheld RFID readers ranges from 85-95%. As for speed, it is on average 10 times faster compared to manual RFID readers.

Fully Passive-Printed Wireless Wear Sensor

Wear of abradable materials presents a significant challenge across many industries, where the efficiency, efficacy, and safety of important systems rely on the detection and monitoring of component wear. Three design variations demonstrate real-time monitoring of wear by a novel, additively manufactured, embeddable, and fully passive wireless wear sensor. The three sensor designs incorporate closely spaced, narrow interconnects connected to a parallel resistor circuit, with a passive RFID chip for complete remote operation. The first design includes ten closely spaced horizontal interconnects and tracks wear events orthogonal to the interconnects for a resolution of $200~{\mu }\text{m}$ . The second design divides horizontal interconnects into two interdigitated sets of five lines each to achieve a resolution of $125~{\mu }\text{m}$ . The third design features ten interconnects printed vertically and connected to a sloped drain line to achieve a resolution of $50~{\mu }\text{m}$ . We fabricated all three designs with a single-layer print on machinable glass-ceramics and commercial surface-mount resistors. Lab testing showed that the three sensor designs had an overall experimental resolution of 215.3, 127.8, and $57.34~{\mu }\text{m}$ , respectively. We attribute error to a combination of manufacturing challenges related to the printing of orthogonal and acute angled narrow interconnects, RFID sampling rates, and errors from testing. The maximum error in measured voltage steps for each of the three designs is 10%, 6.67%, and 6.78%. This study is limited in sample size due to testing constraints and is presented as proof of concept. Future work should assess the robustness of these designs and processes.

Microfluidic channel-based wireless charging and communication platform for microsensors with miniaturized onboard antenna

A double layer spiral antenna with side length of 380 μm was fabricated by a multi-step electroplating process, and integrated with a commercialized passive RFID chip to realize the RF power harvesting and communication functions of a microsensor. To power up and communicate with the microchips, a single layer spiral reader antenna was fabricated on top of a glass substrate with side length of 1 mm. The microchips and the reader antenna were both optimized at the frequency of 915 MHz. Due to the small size of the reader antenna, the strength of the magnetic field decreased dramatically along the axial direction of the reader antenna, which limited the working distance to within 1 mm. To enclose the microchips within the reading range, a three-layer microfluidic channel was designed and fabricated. The channel and cover layers were fabricated by laser cutting of acrylic sheets, and bonded with the glass substrate to form the channel. To operate multiple microchips simultaneously, separation and focusing function units were also designed. Low loss pump oil was used to transport the microchips flowing inside the channel. Within the reading area, the microchips were powered up, and their ID information was retrieved and displayed on the computer interface successfully.

Wireless Corrosion Sensors: Review and Status

WIRELESS CORROSION SENSORS: Review and StatusThe traditional methods to study corrosion of metallic materials in occluded environments involve external electrical connections to electrochemical instrumentation, and they are intrusive. Advances in microelectronics have made possible new sensors based on RFID and wireless interrogation [1] “Wired” connections could be optical fibers used for spectroscopic detection of species, or for corrosion of metal films for example [4,5]. Publications that discuss probes and sensors with “wired” connections for corrosion are in references [6-16]. Most traditional monitoring techniques characterize the behavior of macroscopic samples either exposed to simulated conditions or exposed in service conditions. Broomfield, et al.[17] recently reviewed techniques for studying corrosion degradation: (1) linear polarization resistance (LPR); (2) critical threshold concentrations of damaging species (e.g. chloride ions, or pH); (3) resistivity of the damaging medium, and; (4) half-cell potential measurements. Methods (1) to (4) average over sample area (e.g, corrosion rate by LPR), or determine the concentrations or permeation rates averaged over large dimensions. These traditional methods have provided a valuable resource for predicting behavior and corrosion failure, but the “wired” approach limits the extension to buried interfaces and isolated damaging fluid exposure. Other approaches designed for industrial conditions are cited by Dean [18], and a new textbook is an excellent resource for a fundamental background on corrosion science [19]. To take advantage of wireless techniques to characterize the corrosion of “buried” metals, New Wireless Sensors should be:(1) Small so that they are not intrusive and do not alter local conditions in occluded regions;(2) Inexpensive so that multiple units can be embedded at distributed locations;(3) Tailored to enable unequivocal predictions of the metal corrosion process intechnological conditions, and; (4) Robust to ensure durability before the onset of corrosionPrevious wireless chemical (corrosion) sensor research involve passive sensors or threshold sensors. For example, a major type of passive RFID sensor (Class A) does not have a corrosion monitoring function. An example was reported by Andringa, et al [20](2005) with a design “window” for exposure of a portion of the sensor antennae to a damaging fluid. If the sensor fails to respond to interrogation, it is assumed to have “failed”. Similar sensors by Dickerson, et al [21](2006) and by Materer, et al [22](2009) have similar functions. However, these techniques can give a false positive, because the failure mechanism may be unrelated to corrosion. Other sensors measure threshold concentrations of damaging species such as H+, or Cl-, or other properties [23-24]. With integrated electronics, one can design the voltage readout function to exclude signals below the desired threshold. A passive RFID chip has been used to exclude measurements of the Cl- ion that were below a threshold concentration [25]. A third sensor type is activated when an embedded conductivity array becomes immersed in a condensed fluid. An “always-on” battery component is embedded with the conductivity array to provide power for the impedance measurement. These and other sensor types will be reviewed.An alternative active sensor design is to use a battery-assisted threshold chip for an “off/on” signal for wireless transmission. A battery is inactive until a damaging fluid arrives at the sensor location, and the battery-sensor turns “on” and powers a transmitter that signals the onset of damaging condition. The relative merit and advantages of the passive, threshold, and active sensors will be described.References available upon request – space in not sufficient

Wirelessly powered micro-tracer enabled by miniaturized antenna and microfluidic channel

A miniaturized antenna, 380μm by 380μm in size, was fabricated and integrated with a commercialized passive RFID chip to form a micro-tracer, whose size was 2mm by 1mm in total. The micro-tracer was wirelessly powered and interrogated by a single layer spiral reader antenna through near field coupling. To maximize the working distance, the resonant frequency of micro-tracer and reader antenna were matched at 840MHz. Due to the ultra small size of the tracer antenna, power transfer efficiency decreased dramatically as the distance between tracer antenna and reader antenna increased, thus the working distance of the microtracer was limited within 1mm. To achieve massive operation of the micro-tracer, a microfluidic platform was fabricated with in channel focusing and separation. Acrylic sheets were laser cut to define the channel and cover structure, then bonded together layer by layer with a glass substrate, on which reader antenna was integrated. Pump oil was used as the fluidic media carrying the micro-tracer flowing inside the microfluidic channel. The wireless power transfer and real-time communication was demonstrated with the micro-tracer flowing above the reader antenna, as the ID of the micro-tracer was retrieved and displayed on a computer screen.

A Batteryless RFID Remote Control System

This paper presents a novel eco-friendly batteryless remote control (RC) system based on a multi-RF identification (RFID) scheme. The proposed RC device does not require the use of batteries or other installed power source. Instead, it relies on passive RFID chips that are remotely powered by an RFID reader. The controlled device (e.g., a TV) incorporates an RFID reader to power up and communicate with the RC. The proposed batteryless RC is composed of an antenna, a plurality of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> passive RFID chips and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> switches, and a multi-port microstrip network that interconnects the various RFID chips, allowing them to share a common antenna. Each key of the RC is associated to an RFID with a unique identifier, which allows the device to be controlled to identify the key pressed by the user. The proposed arrangement ensures that only the chip associated to the pressed key is read by the RFID reader, while the other chips remain inactive. First of all, the system is described including the multi-RFID scheme and the proposed multi-port network. Afterword, a characterization of the contact switches and RFID chips is performed. This is followed by RFID chip impedance matching and switch tuning. A multi-port network is fabricated (in low-cost FR4) and measured in order to access network's behavior depending on some parameters such as the number of ports and distance from the active port to the antenna. Finally, a four-key RC unit is prototyped, and an RFID reader system is integrated in a TV by using an external RFID-to-infrared interface. Four control functionalities are implemented and tested (CH+, CH-, Vol+, and Vol-). Measurements are also conducted to evaluate the system coverage range and line-of-sight capability.