Electromagnetic tracking method and system

1. An electromagnetic tracking system, comprising:

an electromagnetic coil arrangement, the electromagnetic coil arrangement comprising a set of electromagnetic sensors at fixed locations with respect to each other, each of the electromagnetic sensors comprising a planar coil coupled to a conductive layer, the planar coil comprising non-concentric rings;

at least one complementary electromagnectic sensor; and

a processor configured to process a signal comprising data indicative of a mutual inductance between the at least one complementary electromagnetic sensor and each of the set of the electromagnetic sensors of the electromagnetic coil arrangement.

2. The electromagnetic tracking system claim 1 , wherein each of the planar coils is configured such that a drive current applied across the non-concentric rings of the respective planar coil provides a magnetic field, the magnetic field comprising a moment vector that is tilted at an angle from normal to the respective planar coil.

3. The electromagnetic tracking system of claim 1 , wherein at least one electromagnetic sensor is configured to generate three magnetic fields having dipole moment vectors that are generally orthogonal relative to each other.

4. The electromagnetic tracking system of claim 1 , wherein the set of electromagnetic sensors are arranged about a volume in a substantially hexahedron configuration.

5. The electromagnetic tracking system of claim 4 , wherein the set of electromagnetic sensors comprises at least one center electromagnetic sensor located at or near the center of at least one face of the substantially hexahedron configuration.

6. The electromagnetic tracking system of claim 1 , wherein the set of electromagnetic sensors comprises a plurality of electromagnetic sensors located about the periphery of a region.

7. The electromagnetic tracking system of claim 6 , comprising a center electromagnetic sensor located at or near the center of the region.

8. A method of electromagnetic tracking, comprising:

positioning at least one complementary electromagnetic sensor in a volume of interest with respect to a coil arrangement adjacent to the volume of interest, the coil arrangement comprising a set of electromagnetic sensors at fixed locations with respect to each other, each of the electromagnetic sensors comprising a substrate, a conductive layer coupled to the substrate, and a planar coil coupled to the substrate on an opposite side of the substrate from the conductive layer, the planar coil comprising non-concentric rings; and

sensing a magnetic field characteristic of a magnetic field generated by either the at least one complementary electromagnetic sensor or at least one of the set of electromagnetic sensors.

9. The method of claim 8 , comprising inducing a current across at least one planar coil of the set of electromagnetic sensors to generate a magnetic field having a moment vector that is tilted at an angle from the normal to a plane of the respective planar coil.

10. The method of claim 8 , wherein each of the planar coils comprises second non-concentric rings and third non-concentric rings such that the non-concentric rings, the second non-concentric rings, and the third non-concentric rings are configured to form a coil trio and comprising inducing current across the coil trio of at least one of the planar coils to generate three magnetic fields having dipole moment vectors that are generally orthogonal relative to each other.

11. The method of claim 8 , wherein positioning the at least one complementary electromagnetic sensor comprises positioning an instrument in the volume of interest, wherein the instrument is coupled to the at least one complementary electromagnetic sensor.

12. The method of claim 8 , wherein sensing a magnetic field characteristic comprises sensing a mutual inductance between at least one of the electromagnetic sensors and the at least one complementary electromagnetic sensor.

13. The method of claim 12 , comprising:

transmitting a signal indicative of the mutual inductance to a processor; and

processing the signal indicative of the mutual inductance to determine a position and/or orientation of the complementary electromagnetic sensor.