Electrical and Electronic Engineering - Research Publications
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ItemLetter: improved parsimony of genetic risk scores for coeliac disease through refined HLA modelling(WILEY, 2021-03)LINKED CONTENT This article is linked to Sharp et al paper. To view this article, visit https://doi.org/10.1111/apt.15826
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ItemMeander Thin-Film Biosensor Fabrication to Investigate the Influence of Structural Parameters on the Magneto-Impedance Effect(MDPI, 2021-10)Thin-film magneto-impedance (MI) biosensors have attracted significant attention due to their high sensitivity and easy miniaturization. However, further improvement is required to detect weak biomagnetic signals. Here, we report a meander thin-film biosensor preparation to investigate the fabrication parameters influencing the MI effect. Specifically, we hypothesized that an optimal film thickness and sensing area size ratio could be achieved to obtain a maximum MI ratio. A meander multilayer MI biosensor based on a NiFe/Cu/NiFe thin-film was designed and fabricated into 3-, 6-, and 9-turn models with film thicknesses of 3 µm and 6 µm. The 9-turn biosensor resembled the largest sensing area, while the 3- and 6-turn biosensors were designed with identical sensing areas. The results indicated that the NiFe film thickness of 6 µm with a sensing area size of 14.4 mm2 resembling a 9-turn MI biosensor is the optimal ratio yielding the maximum MI ratio of 238%, which is 70% larger than the 3- and 6-turn structures. The 3- and 6-turn MI biosensors exhibited similar characteristics where the MI ratio peaked at a similar value. Our results suggest that the MI ratio can be increased by increasing the sensing area size and film thickness rather than the number of turns. We showed that an optimal film thickness to sensing area size ratio is required to obtain a high MI ratio. Our findings will be useful for designing highly sensitive MI biosensors capable of detecting low biomagnetic signals.
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ItemHeater Integrated Lab-on-a-Chip Device for Rapid HLA Alleles Amplification towards Prevention of Drug Hypersensitivity(MDPI, 2021-05)HLA-B*15:02 screening before administering carbamazepine is recommended to prevent life-threatening hypersensitivity. However, the unavailability of a point-of-care device impedes this screening process. Our research group previously developed a two-step HLA-B*15:02 detection technique utilizing loop-mediated isothermal amplification (LAMP) on the tube, which requires two-stage device development to translate into a portable platform. Here, we report a heater-integrated lab-on-a-chip device for the LAMP amplification, which can rapidly detect HLA-B alleles colorimetrically. A gold-patterned micro-sized heater was integrated into a 3D-printed chip, allowing microfluidic pumping, valving, and incubation. The performance of the chip was tested with color dye. Then LAMP assay was conducted with human genomic DNA samples of known HLA-B genotypes in the LAMP-chip parallel with the tube assay. The LAMP-on-chip results showed a complete match with the LAMP-on-tube assay, demonstrating the detection system's concurrence.
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ItemMagneto-Impedance Biosensor Sensitivity: Effect and Enhancement(MDPI, 2020-09)Biosensors based on magneto-impedance (MI) effect are powerful tools for biomedical applications as they are highly sensitive, stable, exhibit fast response, small in size, and have low hysteresis and power consumption. However, the performance of these biosensors is influenced by a variety of factors, including the design, geometry, materials and fabrication procedures. Other less appreciated factors influencing the MI effect include measuring circuit implementation, the material used for construction, geometry of the thin film sensing element, and patterning shapes compatible with the interface microelectronic circuitry. The type magnetic (ferrofluid, Dynabeads, and nanoparticles) and size of the particles, the magnetic particle concentration, magnetic field strength and stray magnetic fields can also affect the sensor sensitivity. Based on these considerations it is proposed that ideal MI biosensor sensitivity could be achieved when the sensor is constructed in sandwich thick magnetic layers with large sensing area in a meander shape, measured with circuitry that provides the lowest possible external inductance at high frequencies, enclosed by a protective layer between magnetic particles and sensing element, and perpendicularly magnetized when detecting high-concentration of magnetic particles.