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Printing Three-Dimensional Heterogeneities in the Elastic Modulus of an Elastomeric Matrix
Abdel Rahman Abdel Fattah1, Suvojit Ghosh1, Ishwar K Puri1
1Department of Mechanical Engineering and ‡Department of Engineering Physics, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4L7, Canada.
Abstract:
We present a rapid and controllable method to create microscale heterogeneities in the 3D stiffness of a soft material by printing patterns with a ferrofluid ink. An ink droplet moved through a liquid polydimethylsiloxane (PDMS) volume using an externally applied magnetic field sheds clusters of magnetic nanoparticles (MNPs) in its wake. By varying the field spatiotemporally, a well-defined three-dimensional curvilinear feature is printed that contains MNP clusters. Subsequent cross-linking of the PDMS preserves the feature in place after the magnetic field is removed. Since the ferrofluid ink interferes with the cross-linking of PDMS, a 3D print containing ink density variations leads to corresponding spatial deviations in the elastic modulus of the matrix. The modulus is mapped in the experiments with atomic force microscopy. This rapid method to print 3D heterogeneities in soft matter promises the ability to mimic mechanical variations that occur in natural biomaterials.
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