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Patent issued: Fiber array for optical imaging and therapeutics
August 12, 2014
BLACKSBURG, Va., Aug. 12, 2014 – Drs. Christopher Rylander, Thomas A. Campbell, Ge Wang, Yong Xu and Mehmet Alpaslan Kosoglu have been issued a United States Patent for their fiber array for optical imaging and therapeutics invention.
Summary of the Invention:
To address some of the issues relating to light-based therapeutic procedures, embodiments of the present invention provide minimally invasive fiberoptic microneedles (e.g., probes) capable of physically (by way of mechanical means) penetrating tissue to deliver light directly to target areas below the skin surface.
Objects of embodiments of the present invention provide: 1) novel microneedle structures including but not limited to silica solid, hollow-core, and photonic crystal fibers; 2) methods and devices for mechanically (physically) inserting these microneedle fiber arrays into human tissue; and 3) novel biomedical applications involving light/fluid transport through these fibers and tissue for applications including: i) photo-therapy, ii) optical sensing or imaging for diagnostics, iii) fluid/drug delivery, iv) biochemical sensing/diagnostics; and v) multi-modal combinations of the aforementioned applications.
In embodiments of the invention, the fiberoptic microneedle device (FMD) bypasses the turbid skin barrier by insertion of extremely small light-delivering microneedles in proximity to the target tissue. The microneedles are mechanically stabilized to prevent buckling and are painlessly guided into a patient's skin using a novel guidance ferrule template and an elastomeric material. The FMD allows increased light penetration in skin and can substantially improve a variety of light-based therapeutic and diagnostic procedures.
Embodiments of the invention comprise a fiberoptic microneedle or an array of fiberoptic microneedles for light delivery using brightfield imaging in tissue representative phantoms. Embodiments also include a fiberoptic microneedle device (FMD) capable of penetrating skin using white light photographic imaging and thermal imaging during laser irradiation. Methods for using such fiberoptic needles and FMDs to treat a variety of conditions or diseases are also within the scope of the invention.
Fiberoptic microneedles and microneedle devices according to the present invention can comprise a support member for increasing the critical buckling force of the needle(s) to fortify the needles for insertion into skin. It has been found that if a microneedle is embedded inside an elastic medium such as a polymer, the medium will act like a series of springs that limit the lateral movement of the microneedle, increasing its critical buckling force, and enabling skin penetration similar to the mechanism used in mosquito bites.
Further, embodiments of the invention include light guiding microneedles manufactured from standard multimode silica fibers. An exemplary method for manufacturing such fiberoptic needles is by drawing silica fibers into a tapered (needle-like) shape by heating the fibers to their melting temperature and stretching them with a mechanical stage. Such a manufacturing process allows for needles with different geometries to be made, including needles having centimeter lengths and/or sub-micron tip diameters.
A range of various needle geometries have shown potential. For example, using white-light photographic imaging with a stereo microscope, FIG. 3 provides a sequence of photographic images demonstrating the feasibility of 1 mm needle penetration into ex vivo porcine skin. The needle in this example remained intact (buckling not observed) even after removal from the skin, in part due to the high taper angle of the needle. A penetration depth of up to 1 mm is sufficient to bypass the epidermal layer of the skin, which contains melanin, the matter responsible for much of the light absorption in light-based therapeutics.
Embodiments of the invention can also comprise additional mechanical support or strengthening of the needle, for providing a range of feasible microneedle variations for numerous applications. Toward this end, embodiments of devices of the invention can comprise an array of optically transparent fibers (either nano- or microscale in diameter), which are capable of being guided into a patient's skin using a guidance ferrule template and an elastomeric support material for increasing the buckling force of the needle(s).