Microneedles for minimally invasive drug delivery
First Claim
1. A hollow microneedle comprising:
- (a) a generally conical-shaped body having a beveled, non-coring tip, said tip being sharp and able to pierce tissue;
(b) said conical body further having a broad base formed of a substrate at an opposite end from the tip; and
(c) a fluid channel extending through the conical-shaped body, providing fluid communication between said broad base and said tip.
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Accused Products
Abstract
The present invention provides a microneedle incorporating a base that is broad relative to a height of the microneedle, to minimize breakage. The microneedle further includes a fluid channel and a beveled non-coring tip. Preferably arrays of such microneedles are fabricated utilizing conventional semiconductor derived micro-scale fabrication techniques. A dot pattern mask is formed on an upper surface of a silicon substrate, with each orifice of the dot pattern mask corresponding to a desired location of a microneedle. Orifices are formed that pass completely through the substrate by etching. A nitride pattern mask is formed to mask all areas in which a nitride layer is not desired. A nitride layer is then deposited on the bottom of the silicon substrate, on the walls of the orifice, and on the top of the silicon substrate around the periphery of the orifice. The nitride layer around the periphery of the orifice is offset somewhat, such that one side of the orifice has a larger nitride layer. Anisotropic etching is used to remove a substantial portion of the substrate, creating a plurality of angular, blunt, and generally pyramidal-shaped microneedles. A subsequent removal of the nitride layer, followed by an isotropic etching step, softens and rounds out the blunt angular microneedles, providing generally conical-shaped microneedles. The uneven nitride layer adjacent the orifice ensures that the microneedles will include a beveled tip. Such microneedle arrays are preferably incorporated into handheld diagnostic and drug delivery systems.
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Citations
44 Claims
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1. A hollow microneedle comprising:
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(a) a generally conical-shaped body having a beveled, non-coring tip, said tip being sharp and able to pierce tissue;
(b) said conical body further having a broad base formed of a substrate at an opposite end from the tip; and
(c) a fluid channel extending through the conical-shaped body, providing fluid communication between said broad base and said tip. - View Dependent Claims (2, 3, 4)
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5. Apparatus for conveying a fluid transcutaneously, comprising:
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(a) a substrate, said substrate comprising at least one inlet, and a plurality of outlets in fluid communication with said at least one inlet; and
(b) a plurality of microneedles arranged in an array and extending substantially outwardly from said substrate, each microneedle including;
(i) a generally conical-shaped body having a beveled, non-coring tip, said tip being sharp and able to pierce tissue;
(ii) said conical body further having a broad base formed of the substrate at an opposite end from the tip; and
(iii) a fluid channel extending through the conical-shaped body, providing fluid communication between one of the outlets disposed said broad base is formed from the substrate and said tip. - View Dependent Claims (6, 7, 8, 9)
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10. A method of manufacturing a hollow microneedle, comprising the steps of:
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(a) providing a substrate;
(b) forming a fluid channel within said substrate, such that said fluid channel passes through said substrate; and
(c) removing a substantial portion of said substrate, thereby leaving a remainder, said remainder surrounding said fluid channel and being generally conical in shape, such that said fluid channel is generally disposed along a central axis of the conical shape. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 19, 20, 21)
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18. A method of manufacturing an array of hollow microneedles, comprising the steps of:
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(a) providing a silicon substrate;
(b) preparing a dotted mask on an upper surface of said silicon substrate, such that openings in said dotted mask correspond to desired locations for said hollow microneedles in the array;
(c) etching said silicon substrate so as to form a plurality of fluid channels that extend substantially through said silicon substrate;
(d) forming a nitride mask such that said nitride mask covers areas in which no nitride layer is desired;
(e) forming a nitride layer, such that said nitride layer is deposited on the substrate in the areas not covered by the nitride mask;
(f) removing said nitride mask;
(g) performing a bevel etch upon said substrate, thereby forming an array of blunt, angular microneedles;
(h) removing said nitride layer; and
(i) performing a rounding etch to round and sharpen said blunt angular microneedles, thereby completing said array of hollow microneedles.
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22. A minimally invasive diagnostic system for sampling and analyzing a biological fluid from a patient, comprising:
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(a) a handheld diagnostic unit comprising a housing, a processor, a display electrically coupled to said processor, a keypad electrically coupled to said processor, and a memory electrically coupled to said processor;
(b) a disposable cartridge for obtaining a sample of said biological fluid from a patient, said disposable cartridge comprising a housing and an array of microneedles; and
(c) a sensor that when in contact with the sample of the biological fluid, produces a signal indicative of a characteristic of said biological fluid, said sensor being adapted to electrically couple with said processor to provide the signal to the processor for diagnostic processing. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A minimally invasive drug delivery system for transdermally delivering a medicinal fluid into a patient, comprising:
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(a) a handheld control unit comprising a housing, a processor, a display electrically coupled to said processor, a keypad electrically coupled to said processor, a memory electrically coupled to said processor;
a medicinal fluid reservoir, a medicinal fluid outlet in fluid communication with said medicinal fluid reservoir, and an actuator that develops pressure to force the medicinal fluid from the medicinal fluid reservoir and through the medicinal fluid outlet for infusion into the patient, said actuator being electrically coupled to and controlled by the processor;
(b) a disposable cartridge, said disposable cartridge comprising a housing, and an array of microneedles through which the medicinal fluid is infused into the patient; and
(c) a fluid line having a distal end and a proximal end, said proximal end being connected to said medicinal fluid outlet, and said distal end being coupled with said disposable cartridge to provide fluid communication between the medicinal fluid outlet and the disposable cartridge. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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Specification