Passive and wireless displacement measuring device

A method for determining displacement between two objects, comprising the steps of:

• attaching a first end of a magnetic rod to a first object;
• attaching a first end of a sensor coil to a second object;
• wherein the attaching steps are performed such that the rod is partially inserted into the coil and the rod and coil extend between the objects, thereby forming a sensor;
• interrogating the sensor with an interrogation signal;
• and
• receiving a response signal from the sensor, said response signal having a frequency that indicates motion of the rod within the sensor coil;
• wherein the receiving step is performed with at least one receive coil and at least one transmit coil configured in a nulling geometry.

A method for determining displacement between two objects within a living body, comprising the steps of:

• attaching a first end of a magnetic rod to a first skeletal object;
• attaching a first end of a sensor coil to a second skeletal object;
• wherein the attaching steps are performed such that the rod is partially inserted into the coil and the rod and coil extend between the objects, thereby forming a sensor;
• interrogating the sensor with an interrogation signal;
• receiving a response signal from the sensor, said response signal having a frequency that indicates motion of the rod within the sensor coil;
• wherein the receiving step is performed with at least one receive coil and at least one transmit coil configured in a nulling geometry.