Method and apparatus for sensing field strength signals to estimate location of a wireless implantable marker

Abstract

Embodiments of the invention are directed to an apparatus for use in a system that senses an excitable wireless target capable of being implanted in a body or tissue. The apparatus includes multiple electromagnetic field sensors arranged approximately in a common plane, and multiple sense signal output paths coupled to the sensors. Each one of the sensors and corresponding output paths is configured to provide an output signal representing at least a portion of an electromagnetic field provided by the marker, where the output signal is proportional to a component of the field at the sensor, where that component is substantially perpendicular to the plane. Various other configurations regarding this apparatus, as well as the overall system and methods of exciting and receiving signals from wireless markers, are also disclosed.

1 - 53 . (canceled) 
     
     
         54 . A method of manufacturing a system for sensing and localizing a wireless marker configured to wirelessly transmit a marker signal in response to a wirelessly transmitted excitation signal, comprising:
 selecting a sensing distance at which a sensor array is to be positioned from the marker in operation based upon the marker signal; and   providing a sensing system having a support member and a plurality of field sensors carried by the support member, the field sensors being arranged in a locally planar array relative to one another and responsive to magnetic field components at least substantially normal to the field sensors, and the field sensors being arranged in an array having maximum dimension of approximately 100% to 300% of the sensing distance.   
     
     
         55 . The method of  claim 54  wherein providing a sensing system further comprises arranging the field sensors in an array occupying an area having a maximum dimension of approximately 200% of the sensing distance. 
     
     
         56 . A method of manufacturing a system for sensing and localizing a wireless marker configured to wirelessly transmit a marker signal in response to a wirelessly transmitted excitation signal, comprising:
 selecting a sensing distance at which a sensor array is to be positioned from the marker in operation based upon the marker signal;   providing a sensing system having a support member and a plurality of field sensors carried by the support member, the field sensors being arranged in a locally planar array relative to one another and responsive to field components at least substantially normal to the field sensors, and the field sensors being arranged in an array having maximum dimension of approximately 100% to 300% of the sensing distance; and   providing instructions to position the sensing system apart from the marker in operation by a distance at least approximately equal to the sensing distance.