Mechanical characterization of microcapsules with membrane permeability by using indentation analysis

Area of Science:

• Biomaterials Science
• Mechanics of Materials
• Chemical Engineering

Background:

• Microcapsules are essential in drug delivery and encapsulation.
• Understanding their mechanical properties under stress is critical for application design.
• Membrane permeability significantly influences microcapsule behavior but is often simplified in models.

Purpose of the Study:

• To develop a mechanical model for liquid-filled microcapsule indentation that includes membrane permeability.
• To quantify the impact of fluid permeation on microcapsule deformation.
• To identify key parameters governing the force-displacement relationship during indentation.

Main Methods:

• Utilized Kedem and Katchalsky equations to calculate volume changes due to fluid permeation.
• Developed a mechanical model for indentation using a truncated-cone indenter.
• Fitted model predictions to experimental force-displacement data to determine microcapsule properties.

Main Results:

• Successfully modeled microcapsule deformation considering membrane permeability.
• Identified membrane hydraulic permeability, initial stretch, and osmotic pressure as key parameters.
• Demonstrated distinct deformation patterns with and without permeability, highlighting the importance of fluid flow.

Conclusions:

• Membrane permeability plays a significant role in the mechanical response of microcapsules during indentation.
• The developed model accurately captures the force-displacement behavior by incorporating fluid permeation.
• This work provides insights into measuring membrane permeability and understanding microcapsule mechanics.