Chong Lei

A prototype of giant magnetoimpedance-based biosensing system for targeted detection of gastric cancer cells.

A targeted detection of gastric cancer cells is achieved by combining the giant magnetoimpedance (GMI)-based biosensing system and RGD-4C peptide coupled, chitosan covered superparamagnetic iron oxide particles (RGD-Fe(3)O(4)@chitosan). The micro-patterned GMI sensor for targeted detection is made of Co-based ribbon and fabricated by micro electromechanical system (MEMS) technology. Functionalized nanoparticles were designed by coating Fe(3)O(4) with chitosan and conjugating with RGD-4C peptides. The targeted cells were trickled down into the detection area of the system. The detection of each sample is carried out in ten-fold manner and average value is taken as the final result. This system can identify the differences between targeted cells and non-targeted cells. It is of considerable interest due to its potential application in the biomedical field of various specific detections.

Giant magnetoimpedance-based microchannel system for quick and parallel genotyping of human papilloma virus type 16/18

Quick and parallel genotyping of human papilloma virus (HPV) type 16/18 is carried out by a specially designed giant magnetoimpedance (GMI) based microchannel system. Micropatterned soft magnetic ribbon exhibiting large GMI ratio serves as the biosensor element. HPV genotyping can be determined by the changes in GMI ratio in corresponding detection region after hybridization. The result shows that this system has great potential in future clinical diagnostics and can be easily extended to other biomedical applications based on molecular recognition.

An integrated giant magnetoimpedance biosensor for detection of biomarker

A Dynabeads-labeled magnetic immunoassay (MIA) has been developed by using an integrated giant magnetoimpedance (GMI) biosensor for the detection of alpha-fetoprotein (AFP). The GMI biosensor (Cr/Cu/NiFe/Cu/NiFe/Al2O3/Cr/Au films) integrated magnetic sensing elements and a biomolecular immunoplatform. Au film was modified with 11-Mercaptoundecanoic acid (11-MUA) for the immobilization of AFP monoclonal antibody. Double antibody sandwich immunoassay was used to specifically capture and label AFP antigen. Functionalized Dynabeads were conjugated to AFP antigen by streptavidin-biotin binding assay. GMI responses were measured for sensitive detection of AFP from 1 to 10ng/ml. Our results revealed that the presence of AFP on the biosensor improved the GMI effect owing to the induced magnetic dipole of superparamagnetic Dynabeads, and the GMI ratio was greatly increased at high frequency. Specificity of MIA was tested through the use of 1% bovine serum albumin (BSA). The underlying biophysical mechanisms responsible for the enhanced GMI effect in the detection of AFP were discussed. This work provides a complex lab-on-chip MIA for the detection of biomarker, which may open up a new way for the development of GMI-based MIA in clinical trials.

Effect of meander structure and line width on GMI effect in micro-patterned Co-based ribbon

The giant magnetoimpedance (GMI) effect is observed in micro-patterned Co-based commercial amorphous ribbon. The effect of structure (meander, single strip) and line width (200, 400, 600 and 800 µm) on the GMI effect is investigated. The GMI reaches its maximum value of 193.7% in the three-turns meander ribbon with 600 µm line width at a frequency of 20 MHz and a field of 10 Oe. The corresponding GMI sensitivity is 19.4% Oe−1. Meander structure and line width both have a strong influence on the GMI effect. An explanation based on the changes in inductance, resistance and the complex magnetic interaction are presented.

Magnetic impedance biosensor: A review

Though the magnetoimpedance effect was discovered two decades ago, the biomedical applications of the magnetoimpedance sensor are still in their infancy. In this review, the authors summarized the magnetoimpedance effect in soft ferromagnetic wires, ribbons and thin films for biosensing applications. Recent progress and achievements of the magnetoimpedance-based biosensing applications including the detection of magnetic Ferrofluid, magnetic beads, magnetic nanoparticles, magnetically labeled bioanalytes and biomagnetic fields of living systems were reviewed. The modification effect of the biochemical liquids, agglomeration effect of the magnetic particles, and the effect of the stray magnetic field on magnetoimpedance were investigated in this review. Some constructive strategies were proposed for design of the high-performance magnetoimpedance biosensor, for quantitative and ultrasensitive detection of magnetically labeled biomolecules. The theoretical and experimental results suggest that the magnetoimpedance sensors are particularly suitable for highly sensitive detection of low-concentration biomolecules, and might be used for early diagnosis and screening of cancers.

Detection of Dynabeads using a micro-electro-mechanical-systems fluxgate sensor

This paper presents an approach to detect the presence of Dynabeads with a system based on a micro fluxgate sensor fabricated by micro-electro-mechanical systems technology. Due to the excellent performance of the micro fluxgate sensor, the detection system exhibited many advantages, such as lower minimum detectable limit, small weight, and low power consumption. Experimental results show that, applied an external magnetic field in a range of 430 μT to 600 μT, Dynabeads with a concentration as low as 0.1 μg/ml can be detected by this system. Moreover, the detection system could give an approximate quantitation to the magnetic beads.

Fabrication of 3D MEMS toroidal microinductor for high temperature application

Based on Microelectromechanical systems (MEMS) technique and thick photoresist lithography technology, a new toroidal-type inductor for high temperature application has been successfully developed. In the fabrication process, heat-resistant materials are used, alumina as insulator and supporting materials instead of polyimide, heat resistant glass for underlay instead of normal glass, and copper for coil. The maximum inductance is 87nH at 0.826GHz and maximum of quality factor (Q-factor) is 4.63 at 0.786GHz, at room temperature. With simulation of thermal deformation, it shows that the developed toroidal inductor can be suitable for high temperature application, from 300 to 700^oC.

Transverse, longitudinal and perpendicular giant magnetoimpedance effects in a compact multiturn meander NiFe/Cu/NiFe trilayer film sensor

A compact multiturn meander NiFe/Cu/NiFe trilayer film giant magnetoimpedance (GMI) sensor, with the width of 100 µm for NiFe film and 60 µm for Cu film, the space of 40 µm and a turn number of 10 is fabricated by the MEMS technique on a silicon substrate. The transverse, longitudinal and perpendicular GMI effects are respectively investigated in the magnetic field range of 0–120 Oe and the frequency range of 1–40 MHz. With the magnetic field it could be up to 86.6% for the transverse GMI effect at 15 MHz and 120 Oe, 166% for the longitudinal GMI effect at 15 MHz and 20 Oe and 165% for the perpendicular GMI effect at 10 MHz and 50 Oe. In addition, there are platform stages, which correspond to the magnetic field range of 0–20 Oe for the transverse GMI effect and 0–10 Oe for the perpendicular GMI effect. Furthermore, the peak of GMI effects covers a large frequency range, which could be up to about several tens of MHz. The GMI platform and the strong GMI effect could be attributed to the demagnetization effect and enhanced electromagnetic coupling from the compact meander sensor structure, respectively. The broad frequency peak originates from the different magnetization process in the straight segment in the meander structure.

Quantitative determination of magnetic beads using a magnetoimpedance-based lab-on-a-chip platform

This research aims at establishing a lab-on-a-chip platform based on giant magnetoimpedance (GMI) effect for quantitative determination of magnetic beads (MB). A micro-integrated GMI sensor consists of Cr/Cu/NiFe/Cu/NiFe/Al2O3/Cr/Au films that were prepared by Micro-Electro-Mechanical-Systems technology. Au film was integrated into GMI sensor for potential biochemical binding function, and quantitative immobilization of MB was performed on Au film of the GMI sensor. The GMI responses were significantly enhanced at high frequencies after coating MB on the sensing elements. This research offers scientific reference for further study and exploitation on quantitative determination of biomolecules by using the micro-integrated GMI sensor.

One Step Quick Detection of Cancer Cell Surface Marker by Integrated NiFe-based Magnetic Biosensing Cell Cultural Chip

RGD peptides has been used to detect cell surface integrin and direct clinical effective therapeutic drug selection. Herein we report that a quick one step detection of cell surface marker that was realized by a specially designed NiFe-based magnetic biosensing cell chip combined with functionalized magnetic nanoparticles. Magnetic nanoparticles with 20-30 nm in diameter were prepared by coprecipitation and modified with RGD-4C, and the resultant RGD-functionalized magnetic nanoparticles were used for targeting cancer cells cultured on the NiFe-based magnetic biosensing chip and distinguish the amount of cell surface receptor-integrin. Cell lines such as Calu3, Hela, A549, CaFbr, HEK293 and HUVEC exhibiting different integrin expression were chosen as test samples. Calu3, Hela, HEK293 and HUVEC cells were successfully identified. This approach has advantages in the qualitative screening test. Compared with traditional method, it is fast, sensitive, low cost, easy-operative, and needs very little human intervention. The novel method has great potential in applications such as fast clinical cell surface marker detection, and diagnosis of early cancer, and can be easily extended to other biomedical applications based on molecular recognition.