Meander Thin-Film Biosensor Fabrication to Investigate the Influence of Structural Parameters on the Magneto-Impedance Effect

Abstract

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.

Line spacing effect on the giant magnetoimpedance behavior on microribbon with meander type: a comparison of theory and experiment

“…The sensing area and the number of turns of microribbon with meander type are critical to the design of highly sensitive GMI sensors (Sayad et al, 2021). Three different configurations (3, 6 and 9 turns) are designed, and the sensing area is determined by the number of turns and the line width taken by the meander line.…”

“…The sensing area and the number of turns of microribbon with meander type are critical to the design of highly sensitive GMI sensors (Sayad et al. , 2021).…”

“…Ls has not only an influence on the size of the meanders but also is a key factor in determining the accuracy of fabrication of thin-film and microribbon with meander type. Sayad et al used electroplating to obtain thin-film meanders and briefly investigated the effect of Ls on the sensitivity of thin-film meanders (Sayad et al, 2021;Volchkov et al, 2012). Chen et al have reported the dependence of the relative variation of Ls on the GMI performance of microribbon with meander type (Chen et al, 2009;Feng et al, 2019a).…”

“…Sayad et al. used electroplating to obtain thin-film meanders and briefly investigated the effect of Ls on the sensitivity of thin-film meanders (Sayad et al. , 2021; Volchkov et al.…”

Design and Optimisation of Elliptical-Shaped Planar Hall Sensor for Biomedical Applications

“…In addition, several research groups have exploited the applications of magnetoresistive sensors for biomolecular recognition [ 12 , 13 , 14 ]. There are three major categories based on the structures and working principles, such as anisotropic magnetoresistance sensors (AMR), giant magnetoimpedance sensors (GMR) [ 15 , 16 ], and tunnelling magnetoresistance sensors (TMR). The magnetoresistive sensor has good linearity, a simplified fabrication process, and shape flexibility.…”