Since the fundamental discovery of the giant magnetoresistance many spintronic devices have been developed and implemented in our daily life (e.g. information storage and automotive industry). Lately, advances in the sensors technology (higher sensitivity, smaller size) have potentiated other applications, namely in the biological area, leading to the emergence of novel biomedical platforms. In particular the investigation of spintronics and its application to the development of magnetoresistive (MR) biomolecular and biomedical platforms are giving rise to a new class of biomedical diagnostic devices, suitable for bench top bioassays as well as point-of-care and point-of-use devices. Herein, integrated spintronic biochip platforms for diagnostic and cytometric applications, hybrid systems incorporating magnetoresistive sensors applied to neuroelectronic studies and biomedical imaging, namely magneto-encephalography and magneto-cardiography, are reviewed. Also lab-on-a-chip MR-based platforms to perform biological studies at the single molecule level are discussed. Overall the potential and main characteristics of such MR-based biomedical devices, comparing to the existing technologies while giving particular examples of targeted applications, are addressed.

This paper presents a prototype of a platform for biomolecular recognition detection. The system is based on a magnetoresistive biochip that performs biorecognition assays by detecting magnetically tagged targets. All the electronic circuitry for addressing, driving and reading out signals from spin-valve or magnetic tunnel junctions sensors is implemented using off-the-shelf components. Taking advantage of digital signal processing techniques, the acquired signals are processed in real time and transmitted to a digital analyzer that enables the user to control and follow the experiment through a graphical user interface. The developed platform is portable and capable of operating autonomously for nearly eight hours. Experimental results show that the noise level of the described platform is one order of magnitude lower than the one presented by the previously used measurement set-up. Experimental results also show that this device is able to detect magnetic nanoparticles with a diameter of 250 nm at a concentration of about 40 fM. Finally, the biomolecular recognition detection capabilities of the platform are demonstrated by performing a hybridization assay using complementary and non-complementary probes and a magnetically tagged 20mer single stranded DNA target.

Flow cytometers have been optimized for use in portable platforms, where cell separation, identification and counting can be achieved in a compact and modular format. This feature can be combined with magnetic detection, where magnetoresistive sensors can be integrated within microfluidic channels to detect magnetically labelled cells. This work describes a platform for in-flow detection of magnetically labelled cells with a magneto-resistive based cell cytometer. In particular, we present an example for the validation of the platform as a magnetic counter that identifies and quantifies Streptococcus agalactiae in milk.