Microneedle-Tissue Interaction Across Varying Biological and Mechanical Conditions.

Area of Science:

• Biomedical Engineering
• Materials Science
• Tissue Engineering

Background:

• Microneedle (MN)-tissue interactions are crucial for transdermal drug delivery and biosensing.
• Limited mechanistic understanding hinders MN optimization.
• Investigating biological and mechanical factors is essential for improving MN performance.

Purpose of the Study:

• To systematically investigate the impact of biological (tissue type, temperature) and mechanical (MN design, material, insertion velocity) parameters on MN insertion and extraction.
• To evaluate the effect of tissue temperature variations (hypo- and hyperthermia) on MN performance.
• To develop and assess a novel MN design with enhanced tissue adhesion.

Main Methods:

• Experiments conducted on porcine skin, chicken breast, and agarose gel to model diverse tissue properties.
• Analysis of mechanical responses via force-displacement measurements, including insertion force, extraction force, and relaxation time.
• Development and testing of a novel conical MN with integrated surface suction-cup structures.

Main Results:

• Elevated tissue temperature decreased insertion and extraction forces and shortened relaxation times, indicating increased tissue compliance.
• Suction-cup MNs demonstrated significantly enhanced needle-tissue adhesion.
• Chicken breast tissue showed the most substantial increase (over four-fold) in extraction force with suction-cup MNs compared to conventional designs.

Conclusions:

• Tissue temperature and type significantly influence microneedle insertion and extraction dynamics.
• Novel suction-cup microneedle designs offer improved adhesion, crucial for effective transdermal applications.
• Findings provide critical insights for optimizing microneedle design for advanced biomedical applications like drug delivery and biosensing.