Neuromag Oy

Jukka E Knuutila

Juha T Simola

Antti I Ahonen

Visa A Vilkman

Matti J Kajola

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

The invention concerns a pickup coil to measure components of gradients. The coil consists of two pairs of loops connected in series; these pairs are then connected in parallel. The coil so formed has a low inductance, and no shielding currents are induced to superconducting coils in homogeneous magnetic fields. One coil can be employed to measure several field components simultaneously when the coil is coupled to current sensing elements, for example to SQUIDS, so that the current components measured by the sensing elements do not couple magnetically because of the symmetry. This can be accomplished by connecting the said elements between terminals between the loops (5, 6 and 7, 8). The inductance of this coil can be further reduced by subdividing the loops into parts connected in parallel.

Composite pickup coil for measurement of magnetic field components in a

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

Jukka E Knuutila