Abstract
SQUID magnetometers have sufficient sensitivity to detect the weak magnetic fields of the human body. Non-invasive and able to observe directly our electrophysiological activity, they offer the prospect of a new type of functional imaging. The author describes the impact SQUID magnetometer techniques are making in biomedical measurements. He starts by giving a basic introduction to the instrument itself. Next, he introduces the range of biological sources that produce measurable magnetic fields, discussing en route their medical importance and practical measurement problems. Significant topics here are noise reduction and the scope for investigation of the human brain. Finally he indicates the most important issues now confronting biomagnetism researchers as they seek to establish the clinical importance of SQUID magnetometry techniques