Micropipette aspiration method for characterizing biological materials with surface energy

Area of Science:

• Biophysics
• Materials Science
• Cell Biology

Background:

• Soft biological tissues exhibit significant surface stress influencing their biophysical functions.
• Existing mechanical property characterization methods often overlook the crucial role of surface stress.
• Understanding surface effects is vital for accurate biomechanical analysis of tissues and cells.

Purpose of the Study:

• To investigate the micropipette aspiration method for measuring soft tissue mechanical properties, incorporating surface effects.
• To analyze how surface energy influences the aspiration response of biological materials.
• To develop a method for accurately determining elastic modulus in soft tissues and cells.

Main Methods:

• Utilized the micropipette aspiration technique to probe mechanical properties.
• Employed a neo-Hookean constitutive model to represent hyperelasticity.
• Integrated surface effects into a finite element method (FEM) framework.

Main Results:

• Surface energy significantly alters aspiration response when pipette dimensions approach the elastocapillary length.
• Increased surface energy leads to decreased aspiration length and bulk normal stress.
• Failure to account for surface energy results in an overestimation of the elastic modulus.

Conclusions:

• The study provides a framework for incorporating surface stress into mechanical property measurements of soft tissues.
• An explicit relation between applied pressure and aspiration length, considering surface effects, was established.
• This refined method is applicable to various biological tissues and organs, including livers, tumors, and embryos.