Microneedle Geometry
Microneedle Geometry - Related Videos
02:58
Rodent Brain Microinjection Using a Quartz Microneedle
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2025
Source: Paolone, G., et al. Personalized Needles for Microinjections in the Rodent Brain. J. Vis. Exp. (2018).This video demonstrates a rodent brain microneedle injection using a quartz microneedle with holes. The microneedle is attached to a syringe and micropump to control the delivery rate. The needle with the injection solution is inserted into the brain with the delivery speed set at low. Once positioned, the delivery speed is increased. The needle is withdrawn after a brief pause.
02:57
Coordination Number and Geometry
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2020
For transition metal complexes, the coordination number determines the geometry around the central metal ion. Table 1 compares coordination numbers to molecular geometry. The most common structures of the complexes in coordination compounds are octahedral, tetrahedral, and square planar. Coordination Number Molecular Geometry Example 2 linear [Ag(NH3)2]+ 3 trigonal planar [Cu(CN)3]2− 4 tetrahedral(d0 or d10), low oxidation...
02:27
Predicting Molecular Geometry
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2020
VSEPR Theory for Determination of Electron Pair Geometries The following procedure uses VSEPR theory to determine the electron pair geometries and the molecular structures: Write the Lewis structure of the molecule or polyatomic ion. Count the number of electron groups (lone pairs and bonds) around the central atom. A single, double, or triple bond counts as one region of electron density. Identify the electron-pair geometry based on the number of electron groups: linear, trigonal planar,...
08:15
Polymeric Microneedle Array Fabrication by Photolithography
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Cited by 24 •
2015
Here, we present a protocol describing a mold-free fabrication process of the polymeric microneedles by photolithography.
07:41
Fabrication and Characterization of Microneedle Patches for Loading and Delivery of Exosomes
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Cited by 6 •
2024
Exosomes possess significant clinical potential, but their practical application is limited due to easy in vivo clearance and poor stability. Microneedles present a solution by enabling localized delivery by puncturing physiological barriers and dry-state preservation, thereby addressing the limitations of exosome administration and expanding their clinical utility.
FAQs
Performance depends on the interaction among dimensions rather than on any single measurement. Needle height helps determine potential penetration depth, while base width and aspect ratio influence structural strength and insertion force. Tip radius affects how the needle enters tissue. Considering these variables together lets designers balance tissue access with mechanical reliability and limited tissue damage.
Aspect ratio, the relationship between needle height and base width, is a useful design variable because it connects slenderness with mechanical behavior. A geometry with greater height relative to its base may support deeper access, but the design must still provide sufficient strength during insertion. Bioengineers therefore tune aspect ratio alongside material selection and target-tissue requirements.
Changing the tip radius can alter insertion force, penetration depth, mechanical strength, and transport behavior. This makes tip geometry an important control point when a device must enter tissue while preserving structural integrity. Designers adjust the tip in relation to the intended application, material, and tissue so the final device supports effective performance without unnecessary tissue damage.
Array spacing determines how individual needles are arranged across the device and can influence interactions with tissue and the transport of drugs or biological fluids. Spacing must therefore be considered with needle dimensions rather than selected independently. Optimizing the arrangement helps align the array with its intended delivery, sensing, or sampling function.
A practical design process starts by identifying the intended use and target tissue, then selecting needle height, base width, tip radius, aspect ratio, and array spacing. Researchers optimize these dimensions with the chosen material to obtain the desired penetration, insertion behavior, and transport performance. The resulting design is assessed through performance, safety, and tissue-damage considerations.
Different applications emphasize different geometric outcomes. Transdermal delivery requires dimensions that support appropriate drug transport, whereas sample collection must support access to biological fluids. Biosensing and localized therapeutic release likewise depend on matching geometry to the intended tissue interaction and transport pathway. This application-specific tuning helps connect physical design with the desired bioengineering function.
Geometry links device fabrication to performance, safety, and clinical translation. A design must provide the required penetration and transport behavior while maintaining mechanical reliability and limiting tissue damage. Evaluating these factors together helps researchers identify configurations that are not only functional in experiments but also better suited to practical minimally invasive applications.