Medical devices and instruments with non-coated superhydrophobic or superoleophobic surfaces

Abstract

Device surfaces are rendered superhydrophobic and/or superoleophobic through microstructures and/or nanostructures that utilize the same base material(s) as the device itself without the need for coatings made from different materials or substances. A medical device includes a portion made from a base material having a surface adapted for contact with biological material, and wherein the surface is modified to become superhydrophobic, superoleophobic, or both, using only the base material, excluding non-material coatings. The surface may be modified using a subtractive process, an additive process, or a combination thereof. The product of the process may form part of an implantable device or a medical instrument, including a medical device or instrument associated with an intraocular procedure. The surface may be modified to include micrometer- or nanometer-sized pillars, posts, pits or cavitations; hierarchical structures having asperities; or posts/pillars with caps having dimensions greater than the diameters of the posts or pillars.

Claims

1. A medical instrument adapted for use with an intraocular procedure, comprising: a proximal portion configured for grasping by a user; a distal portion including an elongated shaft terminating in a distal tip adapted for use in conjunction with an intraocular procedure; wherein the distal portion is made from a base material having a surface adapted for contact with biological intraocular vitreous material; and wherein the surface of the distal portion of the instrument includes micrometer- or nanometer-sized structures or patterns made only from the base material, causing the distal portion of the instrument to become superhydrophobic, superoleophobic, or both, thereby causing the distal portion of the instrument to repel the vitreous material during the intraocular procedure.

2. The instrument of claim 1, wherein the micrometer- or nanometer-sized structures or patterns are pillars, posts, pits or cavitations using only the base material.

3. The instrument of claim 1, wherein the micrometer- or nanometer-sized structures include hierarchical structures having asperities.

4. The instrument of claim 1, wherein: the micrometer- or nanometer-sized posts or pillars have diameters and upper caps with dimensions greater than the diameters of the posts or pillars.

5. The instrument of claim 1, wherein the micrometer- or nanometer-sized structures or patterns are formed using a subtractive process.

6. The instrument of claim 1, wherein the micrometer- or nanometer-sized structures or patterns are formed using an additive process.

7. The instrument of claim 1, wherein the micrometer- or nanometer-sized structures or patterns are formed using a combination of additive and subtractive processes.

8. The instrument of claim 1, wherein the elongated shaft terminates in intraocular scissors.

9. The instrument of claim 1, wherein the elongated shaft forms part of a vitrectomy probe.

10. The instrument of claim 1, wherein the elongated shaft terminates in intraocular forceps.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic of a preferred structure having a hierarchical surface including asperities;

(2) FIG. 2 is a diagram that shows potential fabrication techniques used to fabricate micron- and nano-scale structures;

(3) FIG. 3A shows an array of pointed conical shapes applicable to the invention;

(4) FIG. 3B shows an array of tapered pillars with caps applicable to the invention;

(5) FIG. 3C shows an array of wider tapered pillars with caps applicable to the invention;

(6) FIG. 3D shows an array of shorter, tapered pillars applicable to the invention;

(7) FIG. 3E shows an array of short, coin-like structures;

(8) FIG. 3F shows an array of narrower, tapered pillars with caps applicable to the invention;

(9) FIG. 4A illustrates a woven superomniphobic surface;

(10) FIG. 4B illustrates a random superomniphobic surface;

(11) FIG. 5A shows a post or pillar having an inverse trapezoidal cross-section;

(12) FIG. 5B shows a post or pillar having a non-inverted trapezoidal cross-section;

(13) FIG. 5C depicts a preferred array of the structures of FIG. 5A;

(14) FIG. 6 is an illustration that depicts intraocular scissors;

(15) FIG. 7 is an illustration that shows a vitrectomy probe; and

(16) FIG. 8 is an illustration that depicts intraocular forceps.

DETAILED DESCRIPTION OF THE INVENTION

(17) This invention improves upon existing designs by providing medical devices with hydrophobic/oleophobic surfaces using the same material(s) that such devices are constructed from; that is, without resorting to coatings. This is significant in that the substances used for such coatings may become detached during use and/or implantation, leading to contamination, infection, and other undesirable side-effects.

(18) FIG. 2 is a diagram that shows potential fabrication techniques used to fabricate micron- and nano-scale structures. In the preferred embodiments, reduction processes (i.e., lithographic and/or etching) are preferred to additive steps such as deposition since the goal is to avoid material coatings. In the most preferred embodiments, e-beam lithographic and/or laser etching steps are used to create an array of pillars on the surface being modified. The invention does not preclude additive processes, however, so long as the same base material of the device is used to produce the additive microstructure. That is, if the base material is metal (i.e., stainless steel, chrome-cobalt, etc.), a metallic microstructure or nanostructure is additively formed to achieve a continuity in material type as opposed to dissimilar materials having a greater tendency to separate and flake off. Thus, processes requiring silicon (including the Bosch process), would not be recommended if a silicon coating is first required.

(19) Different micro-/nanostructures are applicable to the invention depending upon the hydrophobic and/or oleophobic properties to be achieved in view of a given application. FIGS. 3A-3F show arrays of shapes, certain of which may be more effective than other including pointed conical shapes and tapered pillars with and without caps. FIG. 4A illustrates a woven superomniphobic surface, and FIG. 4B illustrates a random superomniphobic surface.

(20) Pillars formed in accordance with the invention may have straight sides or may have tapered sides. Pillars with any cross-sectional shape may be used, including circular or polygonal with 3, 4, 5, 6 or more sides. The pillars may have pointed or semi-pointed upper ends, as shown in FIGS. 3A-3F. Preferably, the pillars have a diameter (D) in the range of 10 microns or less, with a height (H) at least as tall as the pillars are wide. In more preferred embodiments, pillar height is 2-4 times the cross sectional height. Pillar spacing is preferably in the order of one to three times D.

(21) The structures of FIGS. 5A-5C are considered to be particularly effective. FIG. 5A shows a post or pillar having an inverse trapezoidal cross-section; FIG. 5B shows a post or pillar having a non-inverted trapezoidal cross-section, and FIG. 5C depicts a preferred array of the structures of FIG. 5A.

(22) In certain preferred embodiments, the structure is hierarchical (FIG. 1) in the sense that one or more of the tops, sides, or spaces between the pillars includes asperities of height h in the range of 1 micron or less, depending upon the size of the pillars themselves. Preferably, the asperities are from 0.5 to .01 times the nominal thickness of the pillars, more preferably 0.1 times the nominal thickness. Such asperities may be produced via chemical etching following pillar formation.

(23) The above, coating-free hydrophobic/oleophobic surface modifications may be used on any implantable on non-implantable medical device or instrument. Substrates of metal, ceramics—even plastics—may be modified through appropriate engineering modification to the energetic beams/etching modalities. The invention finds particular utility in providing surgical instruments having hydrophobic/oleophobic surfaces, and more particular those used in intraocular procedures. Such instruments include, without limitation, intraocular scissors (FIG. 6); vitrectomy probes (FIG. 7); and intraocular forceps (FIG. 8). Each instrument includes a respective proximal handle portion 602, 702, 802, and an elongated shaft 604, 704, 804 terminating in a distal tip 606, 706, 806 adapted for a particular intraocular procedure. In the event the instrument has one or more sharpened edges, such sharpening may be performed before or after the above surface modification, though sharpening following surface modification is preferred to produce the sharpest edge(s), while ensuring that any loose pillars are sloughed off prior to use: