Projection-based stereolithography for direct 3D printing of heterogeneous ultrasound phantoms

Modern ultrasound (US) imaging is increasing its clinical impact, particularly with the introduction of US-based quantitative imaging biomarkers. Continued development and validation of such novel imaging approaches requires imaging phantoms that recapitulate the underlying anatomy and pathology of interest. However, current US phantom designs are generally too simplistic to emulate the structure and variability of the human body. Therefore, there is a need to create a platform that is capable of generating well-characterized phantoms that can mimic the basic anatomical, functional, and mechanical properties of native tissues and pathologies. Using a 3D-printing technique based on stereolithography, we fabricated US phantoms using soft materials in a single fabrication session, without the need for material casting or back-filling. With this technique, we induced variable levels of stable US backscatter in our printed materials in anatomically relevant 3D patterns. Additionally, we controlled phantom stiffness from 7 to >120 kPa at the voxel level to generate isotropic and anisotropic phantoms for elasticity imaging. Lastly, we demonstrated the fabrication of channels with diameters as small as 60 micrometers and with complex geometry (e.g., tortuosity) capable of supporting blood-mimicking fluid flow. Collectively, these results show that projection-based stereolithography allows for customizable fabrication of complex US phantoms.

A Review on: 3D Printed Orthopaedic Cast for Improved Forearm Fracture Rehabilitation

Forearm fracture has many management related problems. In order to regain its function anatomical reduction and immobility is very necessary. Traditional cast is not a satisfactory cast as it is heavy, poorly ventilated and often causes fracture related complications. The paper deals with application of 3D printing technique for suitable cast for forearm rehabilitation. Novel 3D printed cast is light weighted, ventilated, custom fit, strong and waterproof and substantial improvement over conventional orthopaedic cast. With the development in technology, it is expected that the cost of fabrication and its manufacturing time will be greatly reduced in the coming future. Keywords: bone fracture, immobility, rehabilitation, 3D printing, orthopaedic cast

Modulation of Thermal Transport of Micro-structured Materials from 3D Printing

It is desirable to fabricate materials with adjustable physical properties that can be used in different industrial applications. Since the property of materials is highly dependent on its inner structure, the understanding of structure-property correlation is critical to the design of engineering materials. 3D printing appears as a mature method to effectively produce micro-structured materials. In this work, we created different stainless-steel microstructures by adjusting the speed of 3D printing and studied their relationship between thermal property and printing speed. Microstructure study demonstrates that highly porous structure appears at higher speed, and there is nearly linear relationship between porosity and printing speed. Thermal conductivity of samples fabricated by different printing speeds is characterized, then the correlation among the porosity, thermal conductivity, and scanning speed is established. Based on this correlation, the thermal conductivity of sample can be predicted from its printing speed. We fabricated a new sample at a different speed, and the measurement result of thermal conductivity agrees well with the predicted value from the correlation. To explore thermal transport physics, the effects of the pore structure and temperature on the thermal performance of the printed block are also studied. Our work demonstrates that the combination of the 3D printing technique and the printing speed control can realize regulation of the thermophysical properties of materials.

Biomimetic apposition compound eye fabricated using microfluidic-assisted 3D printing

After half a billion years of evolution, arthropods have developed sophisticated compound eyes with extraordinary visual capabilities that have inspired the development of artificial compound eyes. However, the limited 2D nature of most traditional fabrication techniques makes it challenging to directly replicate these natural systems. Here, we present a biomimetic apposition compound eye fabricated using a microfluidic-assisted 3D-printing technique. Each microlens is connected to the bottom planar surface of the eye via intracorporal, zero-crosstalk refractive-index-matched waveguides to mimic the rhabdoms of a natural eye. Full-colour wide-angle panoramic views and position tracking of a point source are realized by placing the fabricated eye directly on top of a commercial imaging sensor. As a biomimetic analogue to naturally occurring compound eyes, the eye’s full-colour 3D to 2D mapping capability has the potential to enable a wide variety of applications from improving endoscopic imaging to enhancing machine vision for facilitating human–robot interactions.