Active noise compensation for multichannel magnetocardiography in an unshielded environment

W.A.M. Aarnink, P.J. van den Bosch, T.-M. Roelofs, M. Verbiesen, H.J. Holland, H.J.M. ter Brake, H. Rogalla

Research output: Contribution to journalArticleAcademicpeer-review

4 Citations (Scopus)
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Abstract

A multichannel high-Tc-SQUID-based heart scanner for unshielded environments is under development, Outside a magnetically shielded room, sensitive SQUID measurements are possible using gradiometers. However, it is difficult to realize large-baseline gradiometers in high-Tc materials, Therefore, the authors developed two active noise compensation techniques. In the Total Field Compensation technique, a Helmholtz type coil set is placed around the sensors. One magnetometer is used as a zero detector controlling the compensation current through the coil set. For Individual Flux Compensation, the reference signal is sent to the separate SQUIDs (or their flux transformer circuits) to compensate the local environmental noise fluxes, The latter technique was tested on low-Tc rf-SQUID magnetometers, each sensor set to a field resolution SQUID magnetometers, i.e. 0.1 pTRMS/√Hz. The authors were able to suppress the environmental disturbances to such an extent that magnetocardiograms could be recorded in an ordinary environment. Here the two suppression techniques are described and experimental results are presented
Original languageEnglish
Pages (from-to)2470-2473
Number of pages4
JournalIEEE transactions on applied superconductivity
Volume5
Issue number2
DOIs
Publication statusPublished - 1995

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