Document Detail


Effects of Microneedle Design Parameters on Hydraulic Resistance.
MedLine Citation:
PMID:  22211159     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Microneedles have been an expanding medical technology in recent years due to their ability to penetrate tissue and deliver therapy with minimal invasiveness and patient discomfort. Variations in design have allowed for enhanced fluid delivery, biopsy collection, and the measurement of electric potentials. Our novel microneedle design attempts to combine many of these functions into a single length of silica tubing capable of both light and fluid delivery terminating in a sharp tip of less than 100 microns in diameter. This manuscript focuses on the fluid flow aspects of the design, characterizing the contributions to hydraulic resistance from the geometric parameters of the microneedles. Experiments consisted of measuring the volumetric flow rate of de-ionized water at set pressures (ranging from 69-621 kPa) through a relevant range of tubing lengths, needle lengths, and needle tip diameters. Data analysis showed that the silica tubing (~150 micron bore diameter) adhered to within ±5% of the theoretical prediction by Poiseuille's Law describing laminar internal pipe flow at Reynolds numbers less than 700. High hydraulic resistance within the microneedles correlated with decreasing tip diameter. The hydraulic resistance offered by the silica tubing preceding the microneedle taper was approximately 1-2 orders of magnitude less per unit length, but remained the dominating resistance in most experiments as the tubing length was >30 mm. These findings will be incorporated into future design permutations to produce a microneedle capable of both efficient fluid transfer and light delivery.
Authors:
R Lyle Hood; Mehmet A Kosoglu; Matthew Parker; Christopher G Rylander
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Publication Detail:
Type:  JOURNAL ARTICLE    
Journal Detail:
Title:  Journal of medical devices     Volume:  5     ISSN:  1932-619X     ISO Abbreviation:  -     Publication Date:  2011 Sep 
Date Detail:
Created Date:  2012-1-2     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101299321     Medline TA:  J Med Device     Country:  -    
Other Details:
Languages:  ENG     Pagination:  31012-31016     Citation Subset:  -    
Affiliation:
School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA 24061.
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MeSH Terms
Descriptor/Qualifier:
Grant Support
ID/Acronym/Agency:
R21 CA156078-02//NCI NIH HHS

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