Micro-structures with magnetic removal capability and optionally clear optical path

A method comprising:

• controlling, by a controller, a retrieval magnet to apply a magnetic field to a magnetic material of a microneedle embedded in skin tissue such that a tip portion of the microneedle is disposed beneath a surface of the skin, wherein the microneedle is at least partially formed from the magnetic material that is disposed within the tip portion, and wherein the magnetic field is sufficient to retrieve the microneedle from the skin tissue;
• receiving, by the controller from a light sensor, a signal indicative of retrieval of the microneedle from the skin tissue;
• and
• controlling, by the controller, the retrieval magnet to remove the applied magnetic field in response to receiving the signal from the light sensor.

A method comprising:

• embedding a plurality of microneedles in skin tissue such that a respective tip portion of each microneedle is disposed beneath a surface of the skin, wherein the microneedles are detachably coupled to a backing material, and wherein the microneedles are at least partially formed from a magnetic material;
• detaching the backing material from the plurality of microneedles embedded in the skin tissue;
• controlling, by a controller, a retrieval magnet to apply a magnetic field to the magnetic material of the plurality of microneedles embedded in the skin tissue, wherein the magnetic field is sufficient to retrieve the plurality of microneedles from the skin tissue;
• receiving, by the controller from a light sensor, a signal indicative of retrieval of the plurality of microneedles from the skin tissue;
• and
• controlling, by the controller, the retrieval magnet to remove the applied magnetic field in response to receiving the signal from the light sensor.