Abstract
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.
Highlights
There is increasing interest in using high-performance biosensors for biomedical applications.Among them, biosensors based on magneto-impedance (MI) effect are widely used in medical diagnosis as they exhibit high sensitivity and fast response
We review advances in thin films MI effect sensors and consider how the biosensor sensitivity varies based on factors such as design, geometry, materials and fabrication procedures
The MI effect of a magnetic material is usually expressed as the relative change of impedance when an alternating current (AC) flows in a conductor that is submitted to a magnetic field
Summary
There is increasing interest in using high-performance biosensors for biomedical applications. The MI effect of a magnetic material is usually expressed as the relative change of impedance when an AC flows in a conductor that is submitted to a magnetic field. For maximum sensitivity it is crucial to achieve a sharp transverse magnetic anisotropy for thin films biosensor applications. Sensor sensitivity can be described by magneto-resistance (MR) and reactance (MX) They are expressed as the relative change of resistance andmagneto-reactance reactance when an effects.
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