Advances in Magnetoresistive Biosensors

Abstract

Magnetoresistance (MR) based biosensors are considered promising candidates for the detection of magnetic nanoparticles (MNPs) as biomarkers and the biomagnetic fields. MR biosensors have been widely used in the detection of proteins, DNAs, as well as the mapping of cardiovascular and brain signals. In this review, we firstly introduce three different MR devices from the fundamental perspectives, followed by the fabrication and surface modification of the MR sensors. The sensitivity of the MR sensors can be improved by optimizing the sensing geometry, engineering the magnetic bioassays on the sensor surface, and integrating the sensors with magnetic flux concentrators and microfluidic channels. Different kinds of MR-based bioassays are also introduced. Subsequently, the research on MR biosensors for the detection of protein biomarkers and genotyping is reviewed. As a more recent application, brain mapping based on MR sensors is summarized in a separate section with the discussion of both the potential benefits and challenges in this new field. Finally, the integration of MR biosensors with flexible substrates is reviewed, with the emphasis on the fabrication techniques to obtain highly shapeable devices while maintaining comparable performance to their rigid counterparts.

Point-of-care diagnostics for infectious diseases: From methods to devices

“…GMR effect, which was discovered in 1980s, usually happens in a multi-layer structure in which ferromagnetic (FM) and non-magnetic (NM) thin films are deposited alternately [260] , [261] , [262] . However, subsequently studies demonstrated that GMR effect could also happen in inhomogeneous media, granular films for example, which expanded the biomedical applications of GMR biosensors [263] , [264] . Moreover, GMR effect can sense very low magnetic fields, making it very attractive for developing magnetic biosensors for highly sensitive POC detection of infectious diseases.…”

Magnetic-Nanosensor-Based Virus and Pathogen Detection Strategies before and during COVID-19

“…The image in part C adapted from ref 69 is licensed under CC BY-ND 2.0. The image in part D adapted from ref ( 70 ) is licensed under CC BY-ND 2.0.…”

“… 67 With the advancing of thin-film deposition and nanofabrication technologies, the TMR ratio has increased dramatically during the past 20 years from ∼20% to over 200%. 62 , 68 − 70 …”

Serial MTJ-Based TMR Sensors in Bridge Configuration for Detection of Fractured Steel Bar in Magnetic Flux Leakage Testing

“…After the discovery of high magnetoresistance (MR) in ferromagnetic multilayers [ 15 ], MR effect-based sensors, such as anisotropic magnetoresistance (AMR), giant magnetoresistance (GMR), and tunneling magnetoresistance (TMR) sensors, have been widely investigated for the detection of small magnetic fields in various applications [ 16 , 17 , 18 ]. Among these MR sensors, magnetic tunnel junction (MTJ)-based TMR sensors have attracted much attention due to their high MR ratio at room temperature.…”