Magnetic sensing platform technologies for biomedical applications

Abstract

Detection and quantification of a variety of micro- and nanoscale entities, e.g. molecules, cells, and particles, are crucial components of modern biomedical research, in which biosensing platform technologies play a vital role. Confronted with the drastic global demographic changes, future biomedical research entails continuous development of new-generation biosensing platforms targeting even lower costs, more compactness, and higher throughput, sensitivity and selectivity. Among a wide choice of fundamental biosensing principles, magnetic sensing technologies enabled by magnetic field sensors and magnetic particles offer attractive advantages. The key features of a magnetic sensing format include the use of commercially available magnetic field sensing elements, e.g. magnetoresistive sensors which bear huge potential for compact integration, a magnetic field sensing mechanism which is free from interference by complex biomedical samples, and an additional degree of freedom for the on-chip handling of biochemical species rendered by magnetic labels. In this review, we highlight the historical basis, routes, recent advances and applications of magnetic biosensing platform technologies based on magnetoresistive sensors.

Sensor Technologies Empowered by Materials and Molecular Innovations

“…[13] However,h and-held NMR devices that can record spectra with the resolution necessary to precisely transduce the presence of complex molecules in amixture are still elusive.M olecular transducers will likely be the key to enabling portable NMR-based chemical sensors.Inarecently realized sensor system, host molecules are designed with fluorine substitution about an analyte binding pocket. 19 FNMR displays approximately 300 ppm chemical shift dispersion, which is nearly 30 times that of 1 HNMR and 19 F is a100 %-abundant spin-1 = 2 nuclei. In this case,binding of the analytes by the host is not highly specific and the host molecule will ideally bind aw hole class of analytes.I ti s however necessary that the host-analyte association/dissociation rates are slow on the NMR timescale and thereby produce sharp resonances associated with bound and unbound species.T hus,t he 19 FNMR peaks of the host will not broaden or average upon interacting with the analyte as would be the case with ar apid equilibrium on the NMR timescale.T he strategic positioning of fluorine in ah ost molecule is used to create au nique spectral fingerprint for each bound analyte (Figure 7).…”

Ultrasensitive Magnetic Nanoparticle Detector for Biosensor Applications

“…One of the newer applications of GMR technology is in biosensors used for detection of biological and biomolecular agents such as virus particles, proteins, bacteria, or nucleic acids [9,10,11,12,13]. Significant progress has been achieved in magnetic biosensor technology since the concept was first proposed by Baselt et al [9] using micrometer scale GMR sensors through improved control over sensor materials to control domain wall noise and utilization of complex measurements and signal processing methods [12,13,14,15,16,17,18,19,20,21,22,23]. The relatively large sensor-size-to-nanoparticle-size ratios (historically, the ratio of GMR sensor area to a particle area is far in excess of 100) makes sensing of individual nanoparticles or even sensing of a small number of nanoparticles challenging.…”

Perspective: Magnetoresistive sensors for biomedicine

“…72 This perspective will not focus on reviewing all the latest advances in the field as these can be found in several recently published review articles 69,83,84,86 but will rather give some indicative examples of the most recent and most successful biodetection systems that have been or are being developed in order for the reader to get a clearer idea of these newly implemented innovations.…”

“…20 These strategies can expand the dynamic range of MR sensing but may reduce the field sensitivity compared with their normal easy-axis field responses. 69 Some issues such as extra annealing treatments required for a linear response 75,76 as well as noise sources need to be considered additionally.…”

“…For more than a decade, several research groups worldwide are focusing on the design and development of MR biosensing platforms for biomolecular recognition as well as detection and quantification of biological entities. [69][70][71][72][73][74][75][76] These applications are based on the giant magnetoresistance (GMR) [GMR multilayers and spin valves (SVs)] and the tunneling magnetoresistance (TMR) effects.…”