Three-dimensional on-chip magnetic sensor for oscillating magnetic fields

A system for three-dimensional (3D) localization using oscillating magnetic field gradients, comprising:

• a 3D magnetic field gradient generator comprising:
• a first planar electromagnet coil set configured to produce a first oscillating magnetic field gradient with respect to a first axis;
• a second planar electromagnet coil set configured to produce a second oscillating magnetic field gradient with respect to a second axis that is orthogonal to the first axis;
• a third planar electromagnet coil set configured to produce a third oscillating magnetic field gradient with respect to a third axis that is orthogonal to the first and second axes, the first, second, and third planar electromagnet coil sets vertically arranged with respect to the third axis;
• and
• a controller configured to selectively provide alternating-current (AC) power to the first planar electromagnet coil set, to the second planar electromagnet coil set, and/or to the third planar electromagnet coil set to sequentially produce a respective oscillating localization magnetic field gradient with respect to each of the first, second, and third axes, at least a portion of each oscillating localization magnetic field gradient having a monotonically-varying peak magnetic field magnitude along a respective axis that uniquely encodes a relative position along a respective axis;
• and
• a 3D on-chip magnetic sensor comprising:
• a semiconductor chip having a semiconductor substrate;
• a plurality of metal layers disposed on the semiconductor substrate;
• a plurality of insulator layers disposed on the semiconductor substrate, each insulator layer disposed between a pair of neighboring metal layers to form an alternating arrangement of metal layers and insulator layers;
• a plurality of metal vias defined in the insulator layers, each metal via electrically connecting a respective pair of neighboring metal layers;
• a first electrically conductive coil having a plurality of first planar spirals formed by the metal layers and the metal vias, each first planar spiral including a plurality of first interconnected loops wound about a first chip axis, wherein neighboring first planar spirals are electrically connected to each other;
• a second electrically conductive coil having a plurality of second planar spirals formed by the metal layers and the metal vias, each second planar spiral including a plurality of second interconnected loops wound about a second chip axis that is orthogonal to the first chip axis, wherein neighboring second planar spirals are electrically connected to each other;
• a third electrically conductive coil having a third planar spiral formed by at least some of the metal layers and at least some of the metal vias, the third planar spiral including a plurality of third interconnected loops that are wound about a third chip axis that is orthogonal to the first and second chip axes, the metal layers spaced apart along the third chip axis;
• and
• a respective readout circuit electrically coupled to a respective electrically conductive coil, the respective readout circuit disposed in the semiconductor chip, wherein:
• each electrically conductive coil is configured to produce a respective electromagnetic force (EMF) induced by each oscillating localization magnetic field gradient produced by the 3D magnetic field gradient generator, the respective EMF exclusively driving a respective sensor AC through the respective readout circuit, and
• each readout circuit is configured to detect a respective peak voltage magnitude of the respective sensor AC driven exclusively by the respective EME, the respective peak voltage magnitude corresponding to the monotonically-varying peak magnetic field magnitude of each oscillating localization magnetic field gradient produced by the 3D magnetic field gradient generator.

A method of three-dimensional (3D) localization, comprising:

• placing a 3D magnetic sensor within a field of view (FOV) of a 3D magnetic field gradient generator, the 3D magnetic sensor including first, second, and third electrically conductive coils and first, second, and third readout circuits, each readout circuit electrically coupled to a respective electrically conductive coil;
• sequentially producing, with the 3D magnetic field gradient generator, first, second, and third oscillating localization magnetic field gradients with respect to first, second, and third axes, respectively, the first, second, and third axes mutually orthogonal to one another, wherein the FOV corresponds to at least a portion of each oscillating localization magnetic field gradient having a monotonically-varying peak magnitude along a respective axis;
• sequentially inducing first, second, and third electromagnetic forces (EMFs) in each of the first, second, and third electrically conductive coils in the 3D magnetic sensor, the first, second, and third EMFs induced exclusively by the first, second, and third oscillating localization magnetic field gradients, respectively, sequentially produced by the 3D magnetic field generator;
• sequentially exclusively driving, with each of the first, second, and third EMFs in each of the first, second, and third electrically conductive coils, a respective alternating current (AC) through each readout circuit;
• sequentially measuring, with each readout circuit, a respective peak voltage magnitude of each AC driven by each of the first, second, and third EMFs, the respective peak voltage magnitude of each AC driven by each of the first, second, and third EMFs corresponding to the monotonically-varying peak magnitude of each oscillating localization magnetic field gradient;
• and
• determining a relative position of the 3D magnetic sensor, with respect to the 3D magnetic field gradient generator, using the respective peak voltage magnitude of each AC driven by each of the first, second, and third EMFs.