The SQUID (acronym of Superconducting Quantum Inteference Device) is one of the most important devices in the framework of the "small scale" applications of Superconductivity. It is based on the magnetic flux quantisation in a superconducting ring and on the Josephson Effect. In magnetometer configuration, a SQUID is the most sensitive detector of magnetic field; it is able to measure a magnetic field of the order of some billions times smaller than the earth magnetic field.
SQUID magnetometers and gradiometers are employed in advanced measurement techniques and in particular in the study of magnetic fields associated to bioelectrical activity of living organisms (Biomagnetism).
Although SQUID sensors has been employed in biomagnetic measurements since 25 years, only in the last years technology has allowed the fabrication of complex multichannel systems able to provide a direct functional imaging of vital organs such as brain and heart. The main advantages of biomagnetic techniques are given by the absolutely non-invasive method and the time resolution of a few milliseconds.
Under the Progetto Finalizzato "Tecnologie Superconduttive e Criogeniche" and more recentely under the project "Sviluppo di Componentistica Superconduttrice avanzata e sua applicazione a strumentazione biomedica",supported by MIUR, ICIB has acquired the technological capability to develop SQUID-sensor arrays for large multichannel systems for magnetocardiography (MCG) and magnetoencefalography (MEG).
Recently, in the framework of a multidisciplinary collaboration between ICIB, the Zentral Institut fur Medizinische Technik of the Ulm University(DL) and the Advanced Technologies Biomagnetics srl, a 500-channel MEG-system has been developed. Actually, it works at the RKU Hospital in Ulm. Such a helmet system, called ARGOS 500, allows the vectorial measurement of the magnetic field at the scalp over 165 different points simultaneously with an active compensation technique to reduce the background electromagnetic noise. Due to the particular sensor arrangement, it is possible, for the first time, to obtain via a software a virtual sensor fitting the form and the dimension of the patient head. The sensor array employs 495 SQUID magnetometers and 14 reference sensors; they have been designed and fabricated at the ICIB and constist of fully integrated SQUID magnetometers, based on niobium technology, showing a magnetic field spectral noise less then 3fT/Hz1/2. Up to now, ARGOS 500 is the largest multichannel system for biomagnetism in the world.
Actually, ICIB is involved in projects to develop two new prototype MEG-systems which will be installed in the Naples area and at Istituto di Tecnologie Avanzate Biomediche of Chieti University. These incoming systems, together with the other six system for MCG and MEG working in european scientific institutions and hospital, bear evidence of a technological capability useful for both scientific institutions and companies.
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