Magnetic Barcode Research Articles

Stability of Bar Code Information Stored in Magnetic Nanowire Arrays

Firmware applications such as security codes, magnetic keys, and similar products can be stored in magnetic bar codes similar to optical bar codes. This can be achieved on the triangular lattice present in porous alumina, whose pori can be filled by magnetic material, over which magnetic bar codes can be inscribed. We study the conditions to improve the durability of the stored information by minimizing the repulsive energy among wires with parallel magnetization within the same bar but interacting with attractive energy with wires in the neighboring bar. The following parameters are varied to minimize the energy of the system: relative amount of magnetization orientation within the bar code area in any orientation, width of the bars, and distribution of wider bars to the outside or to the inside of the code. It is found that durability of the code is favored for equal amount of magnetization in each direction, abundance of narrow bars trying to locate a few wider ones towards the center. Three real commercial optical bar codes taken at random were mapped into magnetic bar codes; it is found that the corresponding magnetic energies are similar to those analyzed here which provides a realistic test for this approach.

Electrochemical Synthesis of Co-Rich Nanowires for Barcodes

We synthesized three types of magnetic nanowires (Co-Ni-P, Co-Pt-P, and Co-Fe-P) by electrochemical deposition in polycarbonate membranes for use in magnetic barcodes. The nanowires were about 50 nm in diameter and 6 μm in length. The Co-Pt-P nanowires had the highest coercivity and remanence. We used finite elements to calculate the spatial distribution of the stray magnetic fields produced by the barcodes. The Co-Pt-P had the greatest spatial variation which makes it the best composition for the hard magnetic segment of barcode nanowires. These barcode nanowires may be used for magnetic multiplexing detection.

Magnetic barcode imaging for contrast agents.

To demonstrate a new MR imaging approach that unambiguously identifies and quantitates contrast agents based on intrinsic agent properties such as r1 , r2 , r2*, and magnetic susceptibility. The approach is referred to as magnetic barcode imaging (MBI). Targeted and bioresponsive contrast agents were imaged in agarose phantoms to generate T1 , T2 , T2*, and quantitative susceptibility maps. The parameter maps were processed by a machine learning algorithm that is trained to recognize the contrast agents based on these parameters. The output is a quantitative map of contrast agent concentration, identity, and functional state. MBI allowed the quantitative interpretation of intensities, removed confounding backgrounds, enabled contrast agent multiplexing, and unambiguously detected the activation and binding states of bioresponsive and targeted contrast agents. MBI has the potential to overcome significant limitations in the interpretation, quantitation, and multiplexing of contrast enhancement by MR imaging probes. Magn Reson Med 77:970-978, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

The Scanning TMR Microscope for Biosensor Applications.

We present a novel tunnel magnetoresistance (TMR) scanning microscope set-up capable of quantitatively imaging the magnetic stray field patterns of micron-sized elements in 3D. By incorporating an Anderson loop measurement circuit for impedance matching, we are able to detect magnetoresistance changes of as little as 0.006%/Oe. By 3D rastering a mounted TMR sensor over our magnetic barcodes, we are able to characterise the complex domain structures by displaying the real component, the amplitude and the phase of the sensor’s impedance. The modular design, incorporating a TMR sensor with an optical microscope, renders this set-up a versatile platform for studying and imaging immobilised magnetic carriers and barcodes currently employed in biosensor platforms, magnetotactic bacteria and other complex magnetic domain structures of micron-sized entities. The quantitative nature of the instrument and its ability to produce vector maps of magnetic stray fields has the potential to provide significant advantages over other commonly used scanning magnetometry techniques.

Efficient preparation of magnetic quantum dot barcodes.

Quantum dot (QD)-encoded magnetic barcodes were prepared through a highly efficient membrane emulsification-solvent evaporation approach. Our study demonstrates the great potential of these QD-encoded magnetic barcodes for both magnetic separation and multiplex suspension assays.

Magnetic barcode assay for genetic detection of pathogens

The task of rapidly identifying patients infected with Mycobacterium tuberculosis in resource-constrained environments remains a challenge. A sensitive and robust platform that does not require bacterial isolation or culture is critical in making informed diagnostic and therapeutic decisions. Here we introduce a platform for the detection of nucleic acids based on a magnetic barcoding strategy. PCR-amplified mycobacterial genes are sequence-specifically captured on microspheres, labelled by magnetic nanoprobes and detected by nuclear magnetic resonance. All components are integrated into a single, small fluidic cartridge for streamlined on-chip operation. We use this platform to detect M. tuberculosis and identify drug-resistance strains from mechanically processed sputum samples within 2.5 h. The specificity of the assay is confirmed by detecting a panel of clinically relevant non-M. tuberculosis bacteria, and the clinical utility is demonstrated by the measurements in M. tuberculosis-positive patient specimens. Combined with portable systems, the magnetic barcode assay holds promise to become a sensitive, high-throughput and low-cost platform for point-of-care diagnostics.

Hetero-Coated Magnetic Microcarriers for Point-Of-Care Diagnostics

SU8 microcarriers containing magnetic thin film (40 nm cobalt) elements were fabricated by photolithography and thermal evaporation, and included a gold coating on the base. The microcarriers, which can be encoded with a magnetic barcode for later identification in a multiplexed suspension assay, now possess two distinct surfaces for further chemical derivitization. This allows us to attach different bio-molecules to each side, which we suggest, could be used to add a positive control to typical hybridization assays as a test for binding conditions, thus giving confidence against false negative events. As a proof-of-concept we developed a chemical pathway to attach <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$5^{\prime},6^{\prime}$</tex></formula> -tetramethyl rhodamine onto the gold coated side via the growth of a mixed self-assembled monolayer (characterized by Electrochemical Quartz Crystal Microbalance measurements), while also attaching fluorescein to the SU8 side after first adding a homo-bifunctional spacer to the native surface epoxide groups. Fluorescence microscopy was used to verify the success of this strategy and the feasibility of using PicoGreen as a post-hybridization reporter was studied.

RFID 및 USN을 이용한 스마트 도서관리 시스템 개발

중 대형 도서관에는 상당히 많은 양의 도서 및 미디어 관리대상이 있어 이를 효율적으로 관리하는 것이 쉽지 않다. 최근 마그네틱이나 바코드를 대신하여 RFID 기술을 적용하고 있으나 아직까지는 단순한 도서관리나 도난망지용으로만 한정되어 사용되고 있다. 최근 RFID 및 USN 기술의 발전으로 인하여 다양한 산업분야에서 이를 응용한 시스템이 활용되고 있고 기술적 한계를 좁혀감에 따라 도서관에서 효율적으로 도서를 관리할 수 있는 시스템에 대하여 연구하였다. 본 논문에서 제안하는 지능형 도서관리 시스템은 상기 기술을 적용하여 보다 효율적인 도서관리 체계와 사용자에게 다양한 컨텐츠와 편리성을 제공할 수 있는 시스템을 개발하여 기존의 도서관리 시스템의 단순관리 작업을 보다 다양하게 활용할 수 있는 지능형 도서관리 시스템을 개발하였다. It's not easy for medium or large sized libraries to effectively manage their vast array of books and media data. Recently, in place of magnetic stripes and barcodes, RFID technology has been applied on a small scale to simple book management and theft-prevention initiatives. The development of RFID and USN applied systems and technology has led to RFID and USN being used in a diverse range of industrial fields, including book management systems in libraries. Using the aforementioned technology, the intelligent book management system suggested in this thesis can provide a more practical, effective, content-rich and convenient book management system.

Magnetooptical images of inhomogeneous magnetic fields in metallic films with in-plane anisotropy

The magnetooptical (MO) images of the inhomogeneous field created by permanent magnets in magnetic metallic films with in-plane anisotropy are experimentally studied. The MO images recorded using the longitudinal Kerr effect are the superposition of two pictures, namely, a polar-sensitivity MO image and a longitudinal-sensitivity MO image. An analysis of these images after separation shows that the polar-sensitivity MO image reflects the distribution of the inhomogeneous field component that is normal to the surface of an indicator film in an analog manner. The longitudinal-sensitivity MO image reflects the angular distribution of the in-plane component of a stray field in an analog manner. The coincidence of the experimental and corresponding simulated MO images makes it possible to interpret the experimental images. In particular, it is shown that the specific features detected in the topological characteristics of the inhomogeneous field correspond to experimental singular points. Hidden magnetic images (magnetic bar codes) are shown to be visualized with metallic CoFe films. As an example, the stray field of a magnetic system made of cylindrical magnets is mapped.

Microfluidic Generation of Multifunctional Quantum Dot Barcode Particles

We develop a new strategy to prepare quantum dot (QD) barcode particles by polymerizing double-emulsion droplets prepared in capillary microfluidic devices. The resultant barcode particles are composed of stable QD-tagged core particles surrounded by hydrogel shells. These particles exhibit uniform spectral characteristics and excellent coding capability, as confirmed by photoluminescence analyses. By using double-emulsion droplets with two inner droplets of distinct phases as templates, we have also fabricated anisotropic magnetic barcode particles with two separate cores or with a Janus core. These particles enable optical encoding and magnetic separation, thus making them excellent functional barcode particles in biomedical applications.

Silanization of Ag-Deposited Magnetite Particles: An Efficient Route to Fabricate Magnetic Nanoparticle-Based Raman Barcode Materials

Silica-coated Ag nanostructures usable as magnetic nanoparticle-based Raman barcode materials were developed. Initially, 283 nm sized spherical magnetite particles composed of 13 nm sized superparamagnetic Fe(3)O(4) nanoparticles were synthesized, and silver deposition was conducted using butylamine as the reductant of AgNO(3) in ethanol. The Ag-deposited Fe(3)O(4) (Fe(3)O(4)@Ag) particles are found to be efficient surface-enhanced Raman scattering (SERS) substrates with the enhancement factor at 632.8 nm excitation to be about 3 x 10(6). After SERS markers such as benzenethiol, 4-mercaptotoluene, 4-aminobenzenethiol, and 4-nitrobenzenethiol were adsorbed onto the silver surface, poly(allylamine hydrochloride) (PAH) was coated onto them using the layer-by-layer deposition method such that a subsequent base-catalyzed silanization could readily form a 60 nm thick silica shell around the PAH layer by a biomimetic process. The cross-linked silica shells effectively prevented the SERS-marker molecules from being liberated from the surface of the Fe(3)O(4)@Ag particles. Although the gram magnetization decreased nearly to one-half of the initial value because of coating with silver and silica, the remaining magnetization was nonetheless strong enough for the silica-coated Fe(3)O(4)@Ag particles to be used as barcode materials operating via SERS.

Shape-Coded Silica Nanotubes for Multiplexed Bioassay: Rapid and Reliable Magnetic Decoding Protocols

The recent development of 1D barcode arrays has proved their capabilities to be applicable to highly multiplexed bioassays. This article introduces two magnetic decoding protocols for suspension arrays of shape-coded silica nanotubes to process multiplexed assays rapidly and easily, which will benefit the minimization and automation of the arrays. In the first protocol, the magnetic nanocrystals are incorporated into the inner voids of barcoded silica nanotubes in order to give the nanotubes magnetic properties. The second protocol is performed by trapping the barcoded silica nanotubes onto streptavidin-modified magnetic beads. The rapid and easy decoding process was demonstrated by applying the above two protocols to multiplexed assays, resulting in high selectivity. Furthermore, the magnetic bead-trapped barcode nanotubes provided a great opportunity to exclude the use of dye molecules in multiplexed assays by using barcode nanotubes as signals. The rapid and easy manipulation of encoded carriers using magnetic properties could be used to develop promising suspension arrays for portable bioassays.

Digital biomagnetism: Electrodeposited multilayer magnetic barcodes

A novel magnetic encoding technique for performing high-throughput biological assays is presented. Electrodeposited Ni/Cu and Co/Cu multilayer pillar structures with a diameter of 15 μm and a thickness up to 10 μm are presented as “magnetic barcodes”, where the number of unique codes possible increases exponentially with a linear increase in length. A gold cap facilitates the growth of self-assembled monolayers (SAMs), while microdrop printing allows efficient generation of large libraries of tagged probes. Coercivity-tuning techniques are used to exploit a non-proximity encoding methodology compatible with microfluidic flow.

Design and fabrication of SU8 encapsulated digital magnetic carriers for high throughput biological assays

A design of a biological molecule carrier is presented for the application of high throughput multiplexing biological assays. This carrier contains a bit addressable “magnetic barcode” made of either Permalloy or cobalt thin films, sandwiched between two planar SU8 protective layers. We describe how the design of the magnetic carriers is optimized by engineering the coercivity of each barcode element, allowing the number of available signatures to be increased. Fully encapsulated digital magnetic carriers which carry a 5 bit addressable barcode were also fabricated and are presented. Writing and reading of digital carriers were both performed after releasing in dried solution.

Wireless RF communication in biomedical applications

This paper focuses on wireless transcutaneous RF communication in biomedicalapplications. It discusses current technology, restrictions and applications and alsoillustrates possible future developments. It focuses on the application in biotelemetry wherethe system consists of a transmitter and a receiver with a transmission link in between. Thetransmitted information can either be a biopotential or a nonelectric value like arterialpressure, respiration, body temperature or pH value. In this paper the use ofradio-frequency (RF) communication and identification for those applicationsis described. Basically, radio-frequency identification or RFID is a technologythat is analogous to the working principle of magnetic barcode systems. Unlikemagnetic barcodes, passive RFID can be used in extreme climatic conditions—alsothe tags do not need to be within close proximity of the reader. Our proposedsolution is to exploit an exciting new development in making circuits on polymerswithout the need for battery power. This solution exploits the principle of a surfaceacoustic wave (SAW) device on a polymer substrate. The SAW device is a set ofinterdigitated conducting fingers on the polymer substrate. If an appropriate RFsignal is sent to the device, the fingers act as microantennas that pick up thesignal, and this energy is then converted into acoustic waves that travel across thesurface of the polymer substrate. Being a flexible polymer, the acoustic waves causestresses that can either contract or stretch the material. In our case we mainlyfocus on an RF controllable microvalve that could ultimately be used for fertilitycontrol.

Rewritable remote encoding and decoding of miniature multi-bit magnetic tags for high-throughput biological analysis

We have investigated a new magnetic labelling technology for high-throughput biomolecular identification and DNA sequencing. Planar multi-bit magnetic tags comprising a magnetic barcode formed by an ensemble of micron-sized thin film ferromagnetic Co bars and a 15 x 15 micron Au square for immobilization of probe molecules have been designed and fabricated. We show that by using a globally applied magnetic field and magneto-optical Kerr microscopy the magnetic elements in the multi-bit magnetic tags can be addressed individually and encoded/decoded remotely. The power of the approach is the read/write technique, which allows modest globally applied magnetic fields to write almost unlimited numbers of codes to populations of tags rather than individuals. The magnetic nature of the technology also lends itself naturally to fast, remote decoding and the ability to rewrite tags if needed. We demonstrate the critical steps needed to show the feasibility of this technology, including fabrication, remote writing and reading, and successful functionalization of the tags as verified by fluorescence detection. This approach is ideal for encoding information on tags in microfluidic flow or suspension, in order to label oligonucleotides during split-and-mix synthesis, and for combinatorial library-based high-throughput multiplexed bioassays.

E-Passport Threats

The International Civil Aviation Organization (ICAO) standardized e-passports by specifying how to implement and protect machine-readable travel documents. E-passports have embedded contactless chips that can be read by radio from tip to a few centimeters away. The ICAO chose this technology over magnetic strips and 2D barcodes because it provides reliable connection, large memory capacity, random access, and rewritable memory. As with many other RFID devices, the chip in e-passports uses a 32-bit number for collision avoidance. Every country maintains its own public-key infrastructure (PKI) and exchanges root certificates with other countries via diplomatic means. Agencies issuing e-passports have their own public keys and certificates from the PKI. In this way, a passive authentication mechanism verifies every data group's digest. With today's e-passports, private information is limited to the MRZ and a digital picture, but the goal is to eventually add more biometrics at some point, along with a digitized handwritten signature.

Tuning the ferromagnetism of one-dimensionalFe∕Pt∕Femultilayer barcode nanowires via the barcode layer effect

Using first-principles density functional theory, we have predicted equilibrium structures and electronic and magnetic properties of one-dimensional ferromagnetic $\mathrm{Fe}∕\mathrm{Pt}∕\mathrm{Fe}$ multilayer barcode nanowires. By increasing the thickness of the Pt layer and consequently reducing the thickness of the Fe layer in the nanowire in the ferromagnetic configuration, we found that the average magnetic moment per iron atom, ${\ensuremath{\mu}}_{av}$, increases monotonically with an $\ensuremath{\sim}1∕N(\mathrm{Fe})$ dependence, where $N(\mathrm{Fe})$ is the number of Fe layers. The monotonic increase in average magnetic moment is attributed to the change in magnetic moment at the Fe-Pt interface, and a simple model is proposed to explain this $\ensuremath{\sim}1∕N(\mathrm{Fe})$ variation of ${\ensuremath{\mu}}_{av}$ in the barcode wires. Modulation of the ferromagnetism based on the number of ferromagnetic and nonmagnetic layer sequences in the nanowire suggests the possible application of these nanowires in nanometer scale magnetic barcodes. Furthermore, analysis of the Kohn-Sham energy bands in barcode nanowires suggests strong dependence of spin-polarized conductance on the nonmagnetic Pt spacer layer thickness, opening up the possibility for their application in magnetoelectronics or spintronics.

Hybridization of Electrodeposited Magnetic Multilayer Micropillars

A novel magnetic encoding technique for performing high-throughput biological assays using molecular probes such as antibodies and DNA oligonucleotides is presented. Electrodeposited Ni/Au multilayer pillar structures with diameters from 5-20 mum and thicknesses from 1-10 mum are presented as "magnetic barcodes," where the number of unique codes possible increases exponentially with a linear increase in pillar size. We have successfully functionalized these pillars using a HS-C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> -NHS self-assembled monolayer (SAM) grown on the Au cap layer and attachment of an NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> modified primer oligo sequence and have shown hybridization and denaturation to a fluorescent template. In addition we have developed a novel release layer methodology that allows a large library of probes to be inkjet printed on a single 5 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> chip prior to release.

Massive Fabrication of Free-Standing One-Dimensional Co/Pt Nanostructures and Modulation of Ferromagnetism via a Programmable Barcode Layer Effect

Massive fabrication of free-standing Co/Pt magnetic barcode nanowires with well-defined interfaces and layer thicknesses is obtained after freeing them from porous templates. Such barcodes display bamboo-like shapes with identical motifs either inside or out of the templates. The ferromagnetism of these barcode nanowires can be modulated easily depending on the cobalt segments and shape anisotropies. Further enhancements of the ferromagnetism of Co/Pt barcodes are also accomplished through interfacial alloying processes via a thermally induced phase transition.