Sensitivity maps and system requirements for magnetic induction tomography using a planar gradiometer

Javier Rosell*, Roberto Casañas, Hermann Scharfetter

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We evaluated analytically and experimentally the performance of a planar gradiometer as a sensing element in a system for magnetic induction tomography. A system using an excitation coil and a planar gradiometer was compared against a system with two coils. We constructed one excitation coil, two different sensing elements and a high-resolution phase detector. The first sensor was a PCB square spiral coil with seven turns. The second sensor was a PCB planar gradiometer with two opposite square spirals of seven turns, with a distance between centres of 8 cm. Theoretical sensitivity maps were derived from basic equations and compared with experimental data obtained at 150 kHz. The experimental sensitivity maps were obtained measuring the perturbation produced by a brass sphere of 12 mm in empty space. The advantage of using a gradiometer is that it can be adjusted to give a minimum signal for homogeneous objects, while increasing the sensitivity to local perturbations of the conductivity. Results show that a system using a planar gradiometer as detector has less demanding requirements for the electronic system than a system using simple coils.

Original languageEnglish
Pages (from-to)121-130
Number of pages10
JournalPhysiological Measurement
Issue number1
Publication statusPublished - 14 Mar 2001


  • Bioimpedance
  • Eddy currents
  • Electromagnetic tomography
  • Magnetic induction
  • Planar gradiometer

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Biomedical Engineering
  • Physiology (medical)

Fields of Expertise

  • Human- & Biotechnology

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