5 research outputs found

    Magnetoresistive biosensors for on-chip detection and localisation of paramagnetic particles

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    This paper presents the design and the implementation of an on-chip magnetoresistive sensors array for cell detection and localisation. Giant magnetoresistance (GMR) sensors have been used due to their high sensitivity and resolution. A new calibration and localisation algorithm has been coded and implemented. In order to generate the required homogenous magnetic field, a custom 3D printed Hallbach cylinder has been simulated and characterised. The system includes sensory and electronic boards to collect the data and to transfer them to a computing server. The experimental results are displayed in a visual interface. Ferrofluid is used to model and simulate the magnetic field change of the cell. This paper demonstrates a 4×4 sensors array and provides a step towards the miniaturised on-chip magnetoresistive based cell detection and localisation for portable diagnostics applications

    Magnetoresistive biosensors with on-chip pulsed excitation and magnetic correlated double sampling.

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    Giant magnetoresistive (GMR) sensors have been shown to be among the most sensitive biosensors reported. While high-density and scalable sensor arrays are desirable for achieving multiplex detection, scalability remains challenging because of long data acquisition time using conventional readout methods. In this paper, we present a scalable magnetoresistive biosensor array with an on-chip magnetic field generator and a high-speed data acquisition method. The on-chip field generators enable magnetic correlated double sampling (MCDS) and global chopper stabilization to suppress 1/f noise and offset. A measurement with the proposed system takes only 20 ms, approximately 50× faster than conventional frequency domain analysis. A corresponding time domain temperature correction technique is also presented and shown to be able to remove temperature dependence from the measured signal without extra measurements or reference sensors. Measurements demonstrate detection of magnetic nanoparticles (MNPs) at a signal level as low as 6.92 ppm. The small form factor enables the proposed platform to be portable as well as having high sensitivity and rapid readout, desirable features for next generation diagnostic systems, especially in point-of-care (POC) settings

    Giant Magnetoresistive Biosensor Array for Detecting Magnetorelaxation

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