Detection of magnetically labeled DNA using pseudomorphic AlGaAs∕InGaAs∕GaAs heterostructure micro-Hall biosensors

Abstract

Hall-effect biosensors with a magnetic-field sensitivity of 23nT∕(Hz)1∕2 (30×30μm2, at a drive current of 400μA) were fabricated using pseudomorphic AlGaAs∕InGaAs∕GaAs heterostructures for detection of DNA labeled with magnetic beads. Magnetic beads with diameters of 120 nm were selectively immobilized onto the surfaces of the Hall biosensors using highly specific hybridization of complementary oligonucleotides and were subsequently detected by measurement of the ac magnetic susceptibility of the beads.

Co/Pt Hall sensors for low field detection

“…1. This would then result in a minimum detectable flux change at room temperature Φ~10 -9 Φ 0 , better than most of the Hall sensors available 6,7,8,9 . The smallest possible active area is essential when detecting very inhomogeneous fields, such as those produced by single paramagnetic beads, with a field profile at a distance z above the sensor scaling with their diameter 10 .…”

Novel Nano-Heterostructure Materials and Related Devices

“…Recent applications of Hall effect devices include scanning Hall probe microscopy (SHPM) for magnetic imaging ferromagnetic domains [77][78][79] and more recently biosensing platforms incorporating superparamagnetic labels [80][81][82][83].…”

Magnetic nanoparticles for high-sensitivity detection on nucleic acids via superconducting-quantum-interference-device-based immunomagnetic reduction assay

“…Bio-functionalized magnetic nanoparticles have the potential to be used in bio-applications as contrast reagents in magnetic resonance imaging [1], molecule separation [2], and immunoassays [3][4][5]. In recent years, magnetic nanoparticles have been used as markers for DNA detection [6][7][8][9][10]. A common method for DNA detection involves a target single-strand DNA dispersed in test solution.…”

“…alternative-current (ac) magnetic signals at a fixed frequency are detected. At present, versatile sensors, such as the Faraday coil [7], giant magnetoresistance (GMR) sensor [6], magnetic tunnel junction [8], spin valve [9], Hall probe [10], and superconducting quantum interference device (SQUID) [11] have been proposed to detect ac magnetic signals. The reported sensitivity of these sensors for DNA detection ranges from tens to thousands of pM.…”