An approach towards designing and building of compact low-profile, wideband, unidirectional and conformal imaging antenna for electromagnetic (EM) head imaging systems is presented. The approach includes the realization of a custom-made flexible high-permittivity dielectric substrate to achieve a compact sensing antenna. The developed composite substrate is built using silicon-based poly-di-methyl-siloxane (PDMS) matrix and microscale of aluminium oxide (Al2O3) and graphite (G) powders. Al2O3 and G powders are used as fillers with different weight-ratio to manipulate and control the dielectric properties of the substrate for attaining better matched with the human head and reducing antenna’s physical size while keeping the PDMS flexibility feature. Using the custom-made substrate, a compact, wideband, and unidirectional on-body matched antenna for wearable EM head imaging system is realized. The antenna is configured as a multi-slot planar structure with four shorting pins, working as electric and magnetic dipoles at different frequency bands. The measured reflection coefficient (S11) shows an operating frequency band of 1 -4.3 GHz. The time-average power density and the amplitude of the received signal inside the MRI-based realistic head phantom demonstrate a unidirectional propagation and high-fidelity factor of more than 90%. An array of 13 antennas are fabricated and tested on a realistic 3D head phantom to verify the imaging capability of the proposed antenna. The reconstructed images of different targets inside the head phantom demonstrate the possibility of utilizing the conformal antenna arrays to detect and locate abnormality inside the brain using multistatic Delay-Multiply-And-Sum beamforming algorithm.

The limitations of investment casting of cobalt‐based alloys are claimed to be less problematic with significant improvements in metal additive manufacturing by selective laser melting (SLM). Despite these advantages, the metallic devices are likely to display mechanical anisotropy in relation to build orientations, which could consequently affect their performance “in vivo.” In addition, there is inconclusive evidence concerning the requisite composition and postprocessing steps (e.g., heat treatment to relieve stress) that must be completed prior to using the devices. In the current paper, we evaluate the microstructure of ternary cobalt‐chromium‐molybdenum (Co‐Cr‐Mo) and cobalt‐chromium‐tungsten (Co‐Cr‐W) alloys built with direct metal printing and LaserCUSING SLM systems, respectively, at 0°, 30°, 60°, and 90° inclinations (Φ) in as‐built (AB) and heat‐treated (HT) conditions. The study also examines the tensile properties (Young’s modulus, E; yield strength, R_P0.2; elongation at failure, A_t; and ultimate tensile strength, R_m), relative density (RD), and microhardness (HV5) and macrohardness (HV20) as relevant physicomechanical properties of the alloys. Data obtained indicate improved tensile properties and HV values after a short and cost‐effective heat‐treatment cycle of Co‐Cr‐Mo alloys; however, the process did not homogenize the microstructure of the alloy. Annealing heat treatment of Co‐Cr‐W led to significant isotropic characteristics with increased E and A_t (except for Φ = 90°) in contrast to decreased R_P0.2, R_m, and HV values, compared to the AB form. Similarly, the interlaced weld‐bead structures in AB Co‐Cr‐W were removed during heat treatment, which led to a complete recrystallization of the microstructure. Both alloys exhibited defect‐free microstructures with RD exceeding 99.5%.

There is increasing demand for synthetic bone scaffolds for bone tissue engineering as they can counter issues such as potential harvesting morbidity and restrictions in donor sites which hamper autologous bone grafts and address the potential for disease transmission in the case of allografts. Due to their excellent biocompatibility, titanium scaffolds have great potential as bone graft substitutes as they mimic the structure and properties of human cancellous bone. Here we report on a new thermoset bio-polymer which can act as a binder for Direct Ink Writing (DIW) of titanium artificial bone scaffolds. We demonstrate the use of the binder to manufacture porous titanium scaffolds with evenly distributed and highly interconnected porosity ideal for orthopaedic applications. Due to their porous structure, the scaffolds exhibit an effective Young's modulus similar to human cortical bone, alleviating undesirable stress-shielding effects, and possess superior strength. The biocompatibility of the scaffolds was investigated in vitro by cell viability and proliferation assays using human bone-marrow-derived Mesenchymal stem cells (hMSCs). The hMSCs displayed well-spread morphologies, well-organized F-actin and large vinculin complexes confirming their excellent biocompatibility. The vinculin regions had significantly larger Focal Adhesion (FA) area and equivalent FA numbers compared to that of tissue culture plate controls, showing that the scaffolds support cell viability and promote attachment. In conclusion, we have demonstrated the excellent potential of the thermoset bio-polymer as a Direct Ink Writing ready binder for manufacture of porous titanium scaffolds for hard tissue engineering.

An experimental and numerical study on low-velocity impact responses on [Ti/0/90] _s hybrid titanium composite laminates (HTCLs) is presented. Different energy levels from 10 to 40 J are investigated using a drop-weight instrument and post-impact inspection. An explicit finite element implementation provides a detailed analysis of impact response in composite and titanium layers, respectively. It accounts for interfacial debonding, progressive failure in composite plies and elastic–plastic deformation in titanium. The main failure modes are experimentally and numerically found to be debonding between titanium and composite, matrix cracking and interlaminar delamination. The principal energy-absorbing mechanism is plastic dissipation of the two titanium sheets. The low cost numerical model is able to effectively predict the overall impact response and major failure modes with good accuracy.