Metal detection device and methods of operation thereof

A metal detection device, comprising:

• a handle;
• a shaft extending from the handle;
• a distal sensing portion positioned distally of the shaft, wherein the distal sensing portion comprises:
• a proximal gradiometer comprising a first proximal magnetometer and a second proximal magnetometer,
• a distal gradiometer comprising a first distal magnetometer and a second distal magnetometer,
• wherein the first proximal magnetometer, the second proximal magnetometer, the first distal magnetometer, and the second distal magnetometer are two-axis magnetometers, each having a +x-axis and a +y-axis,
• wherein the +x-axis of the first proximal magnetometer is oriented opposite the +x-axis of the second proximal magnetometer,
• wherein the +y-axis of the first proximal magnetometer is oriented opposite the +y-axis of the second proximal magnetometer,
• wherein the +x-axis of the first distal magnetometer is oriented opposite the +x-axis of the second distal magnetometer, and
• wherein the +y-axis of the first distal magnetometer is oriented opposite the +y-axis of the second distal magnetometer;
• an output component configured to generate a user output to alert a user of a detected object;
• a microcontroller comprising one or more processors and memory units, wherein the one or more processors are programmed to execute instructions stored in the memory units to:
• calculate a differential signal from magnetic field measurements obtained from the first proximal magnetometer, the second proximal magnetometer, the first distal magnetometer, and the second distal magnetometer;
• apply at least one of a signal filter and a derivative to the differential signal calculated to obtain a detection signal, where the signal filter comprises at least one of a high-pass filter and a low-pass filter;
• compare the detection signal against a threshold;
• and
• instruct the output component to generate the user output when the detection signal exceeds the threshold;
• wherein the distal sensing portion further comprises:
• a proximal rigid printed circuit board (PCB), wherein the first proximal magnetometer and the second proximal magnetometer are coupled to the proximal rigid PCB;
• a distal rigid PCB, wherein the first distal magnetometer and the second distal magnetometer are coupled to the distal rigid PCB;
• and
• a distal flexible circuit disposed in between the proximal rigid PCB and the distal rigid PCB and connecting the proximal rigid PCB to the distal rigid PCB,
• wherein the distal rigid PCB is angularly rotated with respect to the proximal rigid PCB about the distal flexible circuit by a twist angle of about 45 degrees.