Benchmarking Mechanical Properties of 3D Printed Elastomeric Microstructures.

Area of Science:

• Materials Science
• Mechanical Engineering
• Additive Manufacturing

Background:

• Characterizing microscale mechanical properties of soft 3D printed materials is challenging due to a lack of standardized methods.
• Existing protocols may overestimate properties due to unaddressed adhesion forces.

Purpose of the Study:

• To develop and validate a standardized microscale nanoindentation protocol for soft 3D printed materials.
• To accurately measure mechanical properties of elastomeric microstructures, considering adhesion effects.

Main Methods:

• Utilized a conospherical indenter tip and a modified trapezoidal displacement profile with lift-off segments.
• Employed the nano-Johnson-Kendall-Roberts model for data analysis.
• Benchmarked against a literature protocol using a Berkovich tip and the Oliver-Pharr model.

Main Results:

• The developed protocol demonstrated accurate characterization of polydimethylsiloxane (PDMS)-based inks.
• Adhesion forces were found to significantly influence mechanical property measurements, causing up to 80% overestimation in other methods.
• Significant differences in results were observed compared to existing state-of-the-art protocols.

Conclusions:

• A standardized microscale nanoindentation protocol is crucial for reliable characterization of soft 3D printed materials.
• Accurate measurement requires accounting for adhesion forces, as demonstrated by the nano-Johnson-Kendall-Roberts model.
• This work enables straightforward and accurate mechanical property assessment in microscale soft 3D printed structures.