title: Printing Three-Dimensional Heterogeneities in the Elastic Modulus of an Elastomeric Matrix.
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.
authors.affiliation: Department of Mechanical Engineering and ‡Department of Engineering Physics, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4L7, Canada.
authors.forename: Abdel Rahman
authors.initials: AR
authors.lastname: Abdel Fattah
authors.affiliation: Department of Mechanical Engineering and ‡Department of Engineering Physics, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4L7, Canada.
authors.forename: Suvojit
authors.initials: S
authors.lastname: Ghosh
authors.affiliation: Department of Mechanical Engineering and ‡Department of Engineering Physics, McMaster University , 1280 Main Street West, Hamilton, Ontario L8S 4L7, Canada.
authors.forename: Ishwar K
authors.initials: IK
authors.lastname: Puri
mesh_terms: D055119:Elastic Modulus; D020724:Elastomers; D011108:Polymers; D011327:Printing; D066330:Printing, Three-Dimensional
chemical_list: D020724:Elastomers; D011108:Polymers; C036925:elastomeric polymer
keywords: elastomer; ferrofluid; material design; nanoparticle; polymer nanocomposite; printing