In this paper, we report a 3D-printed portable microindenter for measuring the mechanical properties of soft materials. The system is composed of three major components: (i) a Z-axis stage, (ii) a force-sensing indentation probe, and (iii) a data acquisition and control system. We construct most of the system parts (including the force sensing probe) by 3D printing, and perform mechanical design and analysis to guarantee the mechanical robustness of the system. The system is capable of performing high-precision, non-destructive material indentation testing with displacement and force sensing resolutions as low as 0.625 μm and 73 μN, respectively. The force-deformation data obtained during indentation are used to determine the mechanical characteristics of a soft material sample based on a Hertz's mechanical model. We also integrate several user-friendly features into the system, including a touch screen and customized software for convenient user-machine interactions. Using the microindenter, we perform elastic testing of polydimethylsiloxane (PDMS) with three base/curing agent ratios (w/w), and achieve consistent results of the materials' Young's moduli in good agreement with the previous results reported in the literature. This proves that our 3D-printed microindenter, although being custom-made and low-cost, maintains the accuracy and repeatability required for soft material testing.
[1]
Walter Michaeli,et al.
Injection Molding: An Introduction
,
1995
.
[2]
Chang Liu,et al.
Re-configurable fluid circuits by PDMS elastomer micromachining
,
1999,
Technical Digest. IEEE International MEMS 99 Conference. Twelfth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.99CH36291).
[3]
Jaydev P. Desai,et al.
Characterization of Soft-Tissue Material Properties: Large Deformation Analysis
,
2004,
ISMS.
[4]
Joong Yull Park,et al.
Increased poly(dimethylsiloxane) stiffness improves viability and morphology of mouse fibroblast cells
,
2010
.
[5]
Joshua M. Pearce.
Open-Source Lab: How to Build Your Own Hardware and Reduce Research Costs
,
2013
.
[6]
Yang Leng,et al.
Materials characterization : introduction to microscopic and spectroscopic methods
,
2013
.
[7]
Joshua M. Pearce,et al.
Open-Source Syringe Pump Library
,
2014,
PloS one.
[8]
Jeremy J. Baumberg,et al.
A one-piece 3D printed microscope and flexure translation stage
,
2015
.
[9]
Richard W Bowman,et al.
A one-piece 3D printed flexure translation stage for open-source microscopy.
,
2015,
The Review of scientific instruments.