SQUID systems for biomagnetic imaging

This review paper illustrates the different SQUID based systems used for bi omagnetic imaging. The review is divided into nine sections. The first thre e sections are introductory: section 1 is a short overview of the topic; se ction 2 summarizes how the biomagnetic fields are generated and what are th e basic mathematical models for the field sources; section 3 illustrates th e principles of operation of the SQUID device. Sections 4-8 are specificall y devoted to the description of the different systems used for biomagnetic measurements: section 4 discusses the different types of detection coils; s ection 5 illustrates the SQUID sensors specifically designed for biomagneti c applications together with the necessary driving electronics, with specia l emphasis on high-temperature superconductivity (HTS) SQUIDS, since HTS de vices are still in a developing stage; section 6 illustrates the different noise reduction techniques; section 7 describes the different multichannel sensors presently operating; and, finally, section 8 gives a hint of what k ind of physiological and/or clinical information may be gathered by the bio magnetic technique. Section 9 suggests some future trends for the biomagnet ic technique.