Neuromag Oy

Visa A Vilkman

Antti I Ahonen

Juha T Simola

Jukka E Knuutila

Matti S Hamalainen

Pasi P Laine

Sensor position indicator coils to be used in magnetoencephalographic experiments and a means of attaching them to the head. The invention comprises a headband (1) and a coil assembly attached to it. The coil assembly consists of a coil set (5) and of at least three fastening strips (6) or of fastening strips having coil sets of individual coils (5') on them. The mechanical properties of the coils are very important. The coil set (5) has three thin- or thick-film coils cast in epoxy resin. The outside surface of the headband (1) and the inside surfaces of the fastening strips (6) have been covered with materials adhering to each other easily. In addition, the underside of the coil set (5) can contain three small knobs, formed during casting, on which the coil set leans when pressed against the head, staying in the tangent plane of the head.

Sensor position indicator coils to be used in magnetoencephalographic

A sensor element of thin film components and fiber glass, and a support structure of fiber glass; when sensor elements are attached to the support structure, a sensor system for magnetoencephalographic measurements is formed. A substrate containing a planar signal coil and a SQUID is attached on a circuit board of fiber glass using a spring cut on the edge of a body plate. On the sensor element, is a small but mechanically stable connector or several such connectors (5); when the sensor element is plugged in receptacles (6) on the support structure (7), the element settles in a well defined orientation. Support structure (7) is made of a fiber glass shell following the shape of the bottom (10) dewar vessel, adapted to the shape of the head. The receptacles (6) are attached to the glass fiber shell by springs (9) made of thin fiber glass plate such that an array covering the whole skull as evenly as possible is formed when the sensor elements are plugged to the receptacles. The spring is cut to enable rotation only around an arbitrary axis in the plane of the spring and a translation only in a direction perpendicular to the plane of the spring. When this support structure is inserted in the dewar, individual sensor elements lean against the dewar bottom (10) by aid of three feet (11), pressed by springs (9), settling perpendicularly to the normal of the dewar bottom passing through the center of the sensor element.

Compact magnetometer probe and an array of them covering the whole human

A superconducting device for measuring weak magnetic fields, especially those generated by the human brain and detected simultaneously over the whole skull. The superconducting magnetometer or gradiometer elements of the device are attached with connectors to a cross-connection/support element which, in turn, is attached to a connecting element containing the electric components necessary for connecting the SQUIDs to the room temperature electronics. The connecting element is attached to a neck plug for the dewar flask. The neck plug is made of a stiff thermal insulation to prevent convection and a ribbon cable containing parallel twisted pairs. The latter element is self-supporting and forms an integral part of the magnetometer support structure. The cables in the neck plug have been made out of wires having a relatively high resistance in order to minimize the heat leak between room temperature and the cryogenic environment of the magnetometers. The excess noise caused by the resistive leads may be compensated by increasing the SQUID gain using positive feedback.

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Helsinki, Finland

Visa A Vilkman