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 μm in diameter. This paper 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 to 621 kPa) through a relevant range of tubing lengths, needle lengths, and needle tip diameters. Data analysis showed that the silica tubing (∼150 μm 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.
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September 2011
Research Papers
Effects of Microneedle Design Parameters on Hydraulic Resistance
R. Lyle Hood,
R. Lyle Hood
School of Biomedical Engineering and Sciences,
Virginia Tech
, Blacksburg, VA
24061
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Mehmet A. Kosoglu,
Mehmet A. Kosoglu
Department of Mechanical Engineering,
Virginia Tech
, Blacksburg, VA
24061
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Matthew Parker,
Matthew Parker
Department of Mechanical Engineering,
Virginia Tech
, Blacksburg, VA
24061
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Christopher G. Rylander
Christopher G. Rylander
School of Biomedical Engineering and Sciences and Department of Mechanical Engineering,
Virginia Tech
, Blacksburg, VA
24061
Search for other works by this author on:
R. Lyle Hood
School of Biomedical Engineering and Sciences,
Virginia Tech
, Blacksburg, VA
24061
Mehmet A. Kosoglu
Department of Mechanical Engineering,
Virginia Tech
, Blacksburg, VA
24061
Matthew Parker
Department of Mechanical Engineering,
Virginia Tech
, Blacksburg, VA
24061
Christopher G. Rylander
School of Biomedical Engineering and Sciences and Department of Mechanical Engineering,
Virginia Tech
, Blacksburg, VA
24061J. Med. Devices. Sep 2011, 5(3): 031012 (5 pages)
Published Online: September 6, 2011
Article history
Received:
December 22, 2010
Revised:
August 1, 2011
Online:
September 6, 2011
Published:
September 6, 2011
Citation
Lyle Hood, R., Kosoglu, M. A., Parker, M., and Rylander, C. G. (September 6, 2011). "Effects of Microneedle Design Parameters on Hydraulic Resistance." ASME. J. Med. Devices. September 2011; 5(3): 031012. https://doi.org/10.1115/1.4004833
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