Abstract:
A method for fabricating a hollow micro-needle array by first providing a silicon substrate; depositing a protective layer on the silicon substrate; defining a plurality of regions for wet etching; wet etching the silicon substrate forming a plurality of recesses that have inclined sidewalls; and continuing processing by electroplating, imaging/developing or micro-machining the plurality of recesses forming a hollow micro-needle array.
Abstract:
A microneedle array module is disclosed comprising a multiplicity of microneedles affixed to and protruding outwardly from a front surface of a substrate to form the array, each microneedle of the array having a hollow section which extends through its center to an opening in the tip thereof. A method of fabricating the microneedle array module is also disclosed comprising the steps of: providing etch resistant mask layers to one and another opposite surfaces of a substrate to predetermined thicknesses; patterning the etch resistant mask layer of the one surface for outer dimensions of the microneedles of the array; patterning the etch resistant mask layer of the other surface for inner dimensions of the microneedles of the array; etching unmasked portions of the substrate from one and the other surfaces to first and second predetermined depths, respectively; and removing the mask layers from the one and the other surfaces. One embodiment of the method includes the steps of: providing an etch resistant mask layer to the other surface of the substrate to a predetermined thickness; patterning the etch resistant mask layer of the other surface to define a reservoir region in the substrate; and etching away the unmasked reservoir region of the substrate to form a reservoir well in the other surface of the substrate. A layer of material may be provided to the other surface to enclose the reservoir well and a passageway is provided through the layer to the well region.
Abstract:
A hollow microneedle with a substantially sharp edge is provided that includes at least one longitudinal blade at the top surface or tip of the microneedle to aid in penetration of the stratum corneum of skin. In a preferred embodiment, there are two such longitudinal blades that are constructed on opposite surfaces at approximately a 180° angle along the cylindrical side wall of the microneedle. Each edged blade has a cross-section that, when viewed from above the microneedle top, has an isosceles triangle profile. The blade's edge can run the entire length of the microneedle from its very top surface to its bottom surface where it is mounted onto the substrate, or the edge can be discontinued partway down the length of the microneedle. A star-shaped solid microneedle also is provided having at least one blade with a relatively sharp edge to assist in penetrating the stratum corneum of skin. In a preferred embodiment, a three pointed star-shape is used, in which each blade has an isosceles triangular cross-section when viewed from the top of the microneedle. The base of each of the isosceles triangles meets at a center of the microneedle to form the star-shaped structure. At least one hole through the substrate is located near the side surfaces of the pairs of blades of the solid microneedle.
Abstract:
Microneedle arrays are fabricated by providing a sacrificial mold including a substrate and an array of posts, preferably solid posts, projecting therefrom. A first material is coated on the sacrificial mold including on the substrate and on the array of posts. The sacrificial mold is removed to provide an array of hollow tubes projecting from a base. The inner and outer surfaces of the array of hollow tubes are coated with a second material to create the array of microneedles projecting from the base. The sacrificial mold may be fabricated by fabricating a master mold, including an array of channels that extend into the master mold from a face thereof. A third material is molded into the channels and on the face of the master mold, to create the sacrificial mold. The sacrificial mold then is separated from the master mold. Alternatively, wire bonding may be used to wire bond an array of wires to a substrate to create the sacrificial mold. The first material preferably is coated on the sacrificial mold by plating. Prior to plating, a plating base preferably is formed on the sacrificial mold including on the substrate and on the array of posts. The inner and outer surfaces of the array of hollow tubes preferably are coated with the second material by overplating the second material on the inner and outer surfaces of the array of hollow tubes.
Abstract:
An array of micro-needles is created by forming an array pattern on the upper surface of a silicon wafer and etching through openings in the pattern to define micro-needle sized cavities having a desired depth. The mold thus formed may be filled with electrically conductive material, after which a desired fraction of the silicon wafer bulk is removed from the bottom-up by etching, to expose an array of projecting micro-needles. The mold may instead be filled with a flexible material to form a substrate useful in gene cell probing. An array of hollow micro-needles may be formed by coating the lower wafer surface with SiN, and etching through pattern openings in the upper surface down to the SiN layer, and then conformally coating the upper surface with thermal silicon dioxide. The SiN layer is then stripped away and a desired fraction of the bulk of the wafer removed from the bottom-up to expose an array of projecting hollow micro-needles.
Abstract:
Microneedle devices for transport of therapeutic and diagnostic materials and/or energy across tissue barriers, and methods for manufacturing the devices, are provided. The microneedles are hollow and/or porous and have diameters between about 10 nm and 1 mm. The microneedle devices permit drug delivery (or removal or sensing of body fluids) at clinically relevant rates across skin or other tissue barriers, without damage, pain, or irritation to the tissue. Microfabrication techniques are used to cost-effectively produce arrays of microneedles from metals, silicon, silicon dioxide, ceramic, and polymeric materials. Methods are provided for making porous or hollow microneedles.
Abstract:
Microneedle devices and methods of manufacture are provided for transport of molecules or energy across or into biological barriers, such as skin. The device can comprise one or more microneedles formed of a first material and a second material, wherein the second material is dispersed throughout the first material or forms a portion of the microneedle. The first material preferably is a polymer. The second material can be pore forming agents, structural components, biosensor, or molecules for release, such as drug. The device also can comprise a substrate and a plurality of microneedles extending from the substrate, wherein the microneedles have a beveled or tapered tip portion, a longitudinally extending exterior channel, or both. Methods of making these devices include providing a mold having a plurality of microdepressions which define the surface of a microneedle; filling the microdepressions with a first molding material; and molding the material, thereby forming microneedles.
Abstract:
Microneedle devices are provided for transport of therapeutic and biological molecules across tissue barriers and for use as microflameholders. In a preferred embodiment for transport across tissue, the microneedles are formed of a biodegradable polymer. Methods of making these devices, which can include hollow and/or porous microneedles, are also provided. A preferred method for making a microneedle includes forming a micromold having sidewalls which define the outer surface of the microneedle, electroplating the sidewalls to form the hollow microneedle, and then removing the micromold from the microneedle. In a preferred method of use, the microneedle device is used to deliver fluid material into or across a biological barrier from one or more chambers in fluid connection with at least one of the microneedles. The device preferably further includes a means for controlling the flow of material through the microneedles. Representative examples of these means include the use of permeable membranes, fracturable impermeable membranes, valves, and pumps.
Abstract:
A device, preferably a micro-device, is molded from a plastic material by injection molding, compression molding or embossing. A microabrader can be molded having microneedles for abrading the stratum corneum of the skin to form an abraded site in the tissue for enhancing drug delivery. The micro-device is molded using a mold assembly having a silicon molding surface. The silicon molding surface can include a recess corresponding to the desired shape and length of the microneedles. The silicon molding surface enables micron and submicron size features to be molded from polymeric materials without the polymeric material adhering to the mold surface. Micro-devices having molded features having micron and submicron dimensions can be rapidly produced without the use of a release agent.