Influence of Array Interspacing on the Force Required for Successful Microneedle Skin Penetration: Theoretical and Practical Approaches

Olatunji, Ololade; Das, Diganta Bhusan; Garland, Martin J.; Belaid, Luc; Donnelly, Ryan F.

doi:10.1002/jps.23439

Cited by 200 publications

(149 citation statements)

References 46 publications

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“…After characterization of 20 samples, the average threshold value is 7.36 6 0.48 N for the microneedles (300 lm at microneedle base and 1000 lm high). Since the minimal force required for a successful penetration is reported to be less than 1 N with the similar microneedle dimension, 37 the device is reliable during the penetration process.…”

Section: B Mechanical Strength Of the Microneedlesmentioning

confidence: 99%

Development of vertical SU-8 microtubes integrated with dissolvable tips for transdermal drug delivery

et al. 2013

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Polymer-based microneedles have drawn much attention in the transdermal drug delivery resulting from their flexibility and biocompatibility. Traditional fabrication approach deploys various kinds of molds to create sharp tips at the end of needles for the penetration purpose. This approach is usually time-consuming and expensive. In this study, we developed an innovative fabrication process to make biocompatible SU-8 microtubes integrated with biodissolvable maltose tips as novel microneedles for the transdermal drug delivery applications. These microneedles can easily penetrate the skin's outer barrier represented by the stratum corneum (SC) layer. The drug delivery device of mironeedles array with 1000 μm spacing between adjacent microneedles is proven to be able to penetrate porcine cadaver skins successfully. The maximum loading force on the individual microneedle can be as large as 7.36 ± 0.48N. After 9 min of the penetration, all the maltose tips are dissolved in the tissue. Drugs can be further delivered via these open biocompatible SU-8 microtubes in a continuous flow manner. The permeation patterns caused by the solution containing Rhodamine 110 at different depths from skin surface were characterized via a confocal microscope. It shows successful implementation of the microneedle function for fabricated devices.

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Section: B Mechanical Strength Of the Microneedlesmentioning

confidence: 99%

Development of vertical SU-8 microtubes integrated with dissolvable tips for transdermal drug delivery

et al. 2013

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“…Henry et al (1998a,b) are widely regarded as the first to have developed a method of transdermal drug delivery using MNs, which has gradually developed for various applications of drug delivery. MN arrays are minimally invasive device that bypass the outer layer of skin, namely the stratum corneum, to achieve enhanced transdermal drug delivery (Prausnitz & Langer, 2008;Donnelly et al, 2012;Olatunji et al, 2013). MN are normally separated into two categories, namely, solid and hollow (Qi et al, 2007;Han et al, 2008;Koelmans et al, 2013).…”

Section: Gas Pressure and Particle Velocitymentioning

confidence: 99%

“…In addition, the skin is generally folded after the insertion of MNs, which may cause MNs to pierce partially, depending on the MN length (Verbaan et al, 2008). Thus, there is a need to understand the required force to insert a given MNs in the skin; the depth of MN penetration into the skin is directly related to the used force for penetration (Donnelly et al, 2010b;Olatunji et al, 2013). In addition, the depth of MN penetration in the skin is dependent on the length of MNs (Badran et al, 2009).…”

Section: Mn Insertion In Skinmentioning

confidence: 99%

Potential of microneedle-assisted micro-particle delivery by gene guns: a review

2013

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“…Silicon microneedles, however, generally either do not satisfy both the scalability and manufacturability required for mass production or are not effective for skin insertion. To satisfy the preceding criteria, silicon microneedles must have the following design specifications: (1) an appropriate base to height ratio (to achieve the mechanical strength required pierce skin efficiently [28]), (2) a beveled tip (to avoid clogging of fluid [29]), (3) appropriate needle height (to effectively deliver drug and/or monitor biomarkers as the skin thickness can differ [30]), and (4) high uniformity with polished surface (to ensure low skin insertion force [31]). …”

Section: Introductionmentioning

confidence: 99%

A repeatable and scalable fabrication method for sharp, hollow silicon microneedles

Kim

Theogarajan

Pennathur

2018

J. Micromech. Microeng.

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Abstract-Scalability and manufacturability are impeding the mass commercialization of microneedles in the medical field. Specifically, microneedle geometries need to be sharp, beveled, and completely controllable, difficult to achieve with microelectromechanical fabrication techniques. In this work, we performed a parametric study using silicon etch chemistries to optimize the fabrication of scalable and manufacturable beveled silicon hollow microneedles. We theoretically verified our parametric results with diffusion reaction equations and created a design guideline for a various set of miconeedles (80 -160 m needle base width, 100 -1000 m pitch, 40 -50 m inner bore diameter, and 150 -350 m height) to show the repeatability, scalability, and manufacturability of our process. As a result, hollow silicon microneedles with any dimensions can be fabricated with less than 2% non-uniformity across a wafer and 5% deviation between different processes. The key to achieving such high uniformity and consistency is a non-agitated HF-HNO 3 bath, silicon nitride masks, and surrounding silicon filler materials with well-defined dimensions. Our proposed method is non-labor intensive, well defined by theory, and straightforward for wafer scale mass production, opening doors to a plethora of potential medical and biosensing applications.

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Influence of Array Interspacing on the Force Required for Successful Microneedle Skin Penetration: Theoretical and Practical Approaches

Cited by 200 publications

References 46 publications

Development of vertical SU-8 microtubes integrated with dissolvable tips for transdermal drug delivery

Development of vertical SU-8 microtubes integrated with dissolvable tips for transdermal drug delivery

Potential of microneedle-assisted micro-particle delivery by gene guns: a review

A repeatable and scalable fabrication method for sharp, hollow silicon microneedles

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