An SU-8 Microgripper Based on the Cascaded V-Shaped Electrothermal Actuators: Design, Fabrication, Simulation and Experimental Investigations

This chapter presents the design, fabrication, numerical simulations and experimental investigations of a polymeric microgripper designed using the cascaded V-shaped electrothermal actuators. The microgripper has a total length around 1 mm and a total thickness of only 20 μm. The microgripper was simulated using electro-thermo-mechanical finite element method (FEM) in order to check the performance of the gripper. As structural material of the microgripper, the SU-8 biocompatible polymer was used during the fabrication process. A fabrication process was implemented to realize the microgripper using a symmetrically sandwich structure. The metallic micro-heaters were encapsulated in the polymeric actuation structure of the microgrippers to reduce the undesirable out-of-plane displacement of the gripper tips and the mechanical stress, to improve the thermal efficiency, and for obtaining the electrical isolation of the structure. Experimental testing has been performed to determine the openings and the temperatures of the microgripper tips as function of electrical current. A displacement of the tips of more than 50 μm can be obtained at an electrical current of around 26–28 mA. A comparison between the simulation results and the measurements were also presented

Development of 3D Bioactive Scaffolds through 3D Printing Using Wollastonite–Gelatin Inks

The bioactivity of scaffolds represents a key property to facilitate the bone repair after orthopedic trauma. This study reports the development of biomimetic paste-type inks based on wollastonite (CS) and fish gelatin (FG) in a mass ratio similar to natural bone, as an appealing strategy to promote the mineralization during scaffold incubation in simulated body fluid (SBF). High-resolution 3D scaffolds were fabricated through 3D printing, and the homogeneous distribution of CS in the protein matrix was revealed by scanning electron microscopy/energy-dispersive X-ray diffraction analysis (SEM/EDX) micrographs. The bioactivity of the scaffold was suggested by an outstanding mineralization capacity revealed by the apatite layers deposited on the scaffold surface after immersion in SBF. The biocompatibility was demonstrated by cell proliferation established by MTT assay and fluorescence microscopy images and confirmed by SEM micrographs illustrating cell spreading. This work highlights the potential of the bicomponent inks to fabricate 3D bioactive scaffolds and predicts the osteogenic properties for bone regeneration applications