Unidirectional magnetic gradiometers

Karp, P.; Duret, D.

doi:10.1063/1.327819

Cited by 28 publications

(10 citation statements)

References 6 publications

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“…Thus, all field components that couple in both coils in the same way are cancelled out. 14 In MPI, this can be adapted to damp the excitation signal. By adding an identical cancellation coil to the other side of the excitation field generator and connecting them counter-rotating, the induced signal will add to nearly zero.…”

Section: Iiib1 Gradiometer Receive Coilmentioning

confidence: 99%

Analog receive signal processing for magnetic particle imaging

et al. 2013

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Section: Iiib1 Gradiometer Receive Coilmentioning

confidence: 99%

Analog receive signal processing for magnetic particle imaging

et al. 2013

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“…The gradiometer sensors (gradient sensors) are commonly used in SQUID magnetometers for the elimination of the influence of ambient fields [54]. These sensors can be also used in other applications where ambient fields disturb the measurements, or determination of the magnetic field gradient itself [55].…”

Section: The Gradiometer Sensorsmentioning

confidence: 99%

Induction coil sensors—a review

Tumański¹

2007

Meas. Sci. Technol.

492

271

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This review describes induction coil sensors, which are also known as search coils, pickup coils or magnetic loop sensors. The design methods for coils with air and ferromagnetic cores are compared and summarized. The frequency properties of coil sensors are analysed and various methods for output signal processing are presented. Special kinds of induction sensors, such as Rogowski coil, gradiometer sensors, vibrating coil sensors, tangential field sensors and needle probes are described. The applications of coil sensors as magnetic antennae are also presented.

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“…In this work, we are going to use inductive decoupling of the drive field coil and the local receive coil by changing the topology of the receive coils. This concept is similar to a gradiometer coil concept [10] which has been proposed by Knopp et al [7] and Graeser et al [8] in combination with MPI. In difference to these concepts, our idea proposes to measure an additional compensation voltage which is used for precise extraction of the nanoparticle signal.…”

Section: The Field Cancelation Receive Coilmentioning

confidence: 93%

A Field Cancellation Signal Extraction Method for Magnetic Particle Imaging

et al. 2015

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In nowadays Magnetic Particle Imaging (MPI) signal detection and excitation happens at the same time. This concept, however, leads to strong coupling of the drive (excitation) field (DF) with the receive chain. As the induced DF signal is several orders of magnitude higher, special measures have to be taken to suppress this signal portion within the receive signal to keep the required dynamic range of the subsequent analog to digital conversion in a technically feasible range. For "frequency space MPI" high-order band-stop-filters have been successfully used to remove the DF signals, which unfortunately as well removes the fundamental harmonic components of the signal of the magnetic nanoparticles (MNP). According to the Langevin theory the fundamental harmonic component has a large signal contribution and is important for direct reconstruction of the particle concentration. In order to separate the fundamental harmonic component of the MNP from the induced DF signal, different concepts have been proposed using signal cancelation based on additional DF signals, also in combination with additional filtering.In this paper, we propose a field-cancelation (FC) concept in which a receive coil (RC) consists of a series connection of a primary coil in combination with an additional cancelation coil. The geometry of the primary coil was chosen to be sensitive for the MNP signal while the cancelation coil was chosen to minimize the overall inductive coupling of the FC-RC with the DF. Sensitivity plots and mutual coupling coefficients were calculated using a thin-wire approximation. A prototype FC-RC was manufactured and effectiveness of the reduction of the mutual inductive coupling (d) was tested in an existing mouse MPI scanner. The difference between simulations (d s =70 dB) and the measurements (d ms =55 dB) indicated the feasibility as well as the need for further investigations.

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Unidirectional magnetic gradiometers

Cited by 28 publications

References 6 publications

Analog receive signal processing for magnetic particle imaging

Analog receive signal processing for magnetic particle imaging

Induction coil sensors—a review

A Field Cancellation Signal Extraction Method for Magnetic Particle Imaging

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