Manufacturing Bits: June 14

3D printed neural networks; photolithographic membranes; on-the-fly printing.


3D printed neural networks
The European Commission has launched a program that will replicate the brain’s neural network using 3D nano-printing.

The program, dubbed the MESO-BRAIN consortium, has received an award of €3.3 million in funding from the European Commission. This research, led by Aston University, also involves Axol Bioscience, Laser Zentrum, the University of Barcelona, the Institute of Photonic Sciences and Kite Innovation.

The project aims to develop 3D human neural networks with specific biological architectures. Researchers, in turn, will gain a better understanding of human disease progression. It will also help improve drug screening efficiency and reduce the need for animal testing.

The project will make use of human-induced pluripotent stem cells (iPSCs). The stem cells have been differentiated into a neuron group. This, in turn, will enable researchers to devise a 3D scaffold or structure to support the development of human neural networks that emulates brain activity.

The structure will be based on a brain cortical module. It will be designed and produced using nano-scale 3D-laser-printed structures. These include nano-electrodes, which will enable electrophysiological analysis of neural network function.

Edik Rafailov, a professor at Aston University and head of the MESO-BRAIN project, said: “What we’re proposing to achieve with this project has, until recently, been the stuff of science fiction. Being able to extract and replicate neural networks from the brain through 3D nanoprinting promises to change this. The MESO-BRAIN project has the potential to revolutionize the way we are able to understand the onset and development of disease and discover treatments for those with dementia or brain injuries.”

Photolithographic membranes
Pennsylvania State University has devised a new type of 3D printing technique to prototype and test polymer membranes.

Polymer or ion exchange membranes are used in fuel cells and certain types of batteries. They can be used in water purification, desalination and related applications.

Most membranes are thin and flat sheets. In simple terms, today’s membrane manufacturing process is expensive and slow. The flow starts with a silicon mold. The mold is etched. Then, a polymer is poured into the mold.

Researchers from Penn State devised a new technique by creating 3D patterns on top of the 2D membrane surface. This, in turn, improves the transport of ions in the membrane.

Researchers devised custom 3D photolithographic printing process. First, a photocurable mixture of ionic polymers is deposited on a surface. Then, the polymers are exposed under a light projector, thereby hardening the base layer. Polymers are added to the base layer. A pattern is projected on the new material to harden the surface, which, in turn, increases the conductivity of the membrane by a factor of two or three.

Patterned membranes using 3D printing (Image: Hickner Group/Penn State)

Patterned membranes using 3D printing (Image: Hickner Group/Penn State)

“Membranes act like a resistor in a battery or fuel cell,” said Michael Hickner, associate professor of materials science and engineering at Penn State, on the university’s Web site. “”If you can lower the resistance by a factor of two or three, you’ve really got something useful.”

Jiho Seo, a Ph.D. candidate in materials science and engineering, added: “While surface-patterned membranes have been studied previously, this is the first 3D printed example of these structures and the first model that really explains the resistance decrease in a quantitative way. A simple parallel resistance model describes the effect of the pattern on lowering the resistance of these new membranes. This insight gives us a design tool to continue to innovate and create new patterns for further improvements along with changing the intrinsic chemistry of the material.”

On-the-fly printing
Cornell University has developed an interactive or “on-the-fly” 3D printer.

The printer makes structures while you are designing them. The system makes use of the so-called “WirePrint” printer. It was developed in collaboration between Guimbretière’s lab and the Hasso Platner Institute.

In 3D printing, a nozzle scans across a stage. It deposits drops of plastic. This, in turn, builds an object in a series of layers.

With WirePrint, the nozzle also extrudes a rope of quick-hardening plastic. This creates a wire frame, which represents the surface of the solid object described in a CAD file. It allows the designer to make refinements while printing is in progress.