Tuesday, January 27, 2015

Star Date: Pretty Darn Soon

The 50th anniversary of Star Trek is a reason to celebrate.
I guess Kirk is too cool to dance and Spock thinks
dancing is illogical.
2016 will mark the 50th anniversary of the first season of the first series of Star Trek. In that first episode we meet James T. Kirk, Dr. McCoy, Spock, Uhuru, and some guy in a red shirt who meets a horrible fate almost immediately.

In the fifty-one years since Gene Roddenberry pitched the series as, “Wagon Train in space meets Gulliver’s Travels,” many of its technological gadgets have come closer to being real. The original series was set in the 2260’s, so we’re way ahead of schedule on producing workable versions of some of those props. For instance, the tricorder sensor was a repurposed salt shaker.

I figure the only decent way to prepare for next year’s 365-day celebration is to describe where we stand in making all those toys a reality. The purpose of this Star Trek refresher is to rekindle, or just plain kindle, a fire in you to finish the research. That, and about three billion dollars of funding should do the trick.

Let’s start with the replicator. Introduced in the original series, the replicator started out as a way to make food and recycle just about anything. In later series, spare parts and just about everything else was made by replicator, including air. The only rules; no weapons and nothing living. Well… we may be able to go Star Trek one better.

The replicator produced the food and the dishware.
Then you could recycle the dirty dishes into your
next martini.
The theory behind the replicator was that it rearranged subatomic particles to produce atoms of different elements. Then these atoms were assembled into whatever material and form were requested. To recycle dirty dishes or that dead Romulan, the replicator would reduce the object to its subatomic particles. Your late night cheeseburger might have been part of a old sock just minutes before.

While we can’t yet manipulate subatomic particles, we have developed ways to make things on demand. It’s called additive manufacturing; you know it better as 3-D printing.

In basic terms, 3-D printing produces a solid object from liquid or solid material in a build up process, as opposed to cutting extraneous material away from a block. In more technical terms, there are several ways to do additive manufacturing.

Stereolithography is the oldest technique for 3-D printing.
Liquid build material is cured using a UV or laser light.
In stereolithography, a vat of liquid plastic is the build material. A thin layer is spread across the build tray and a laser is used to cure the precise areas that correspond to the first layer of the object. The tray is lowered and another thin layer is spread and cured. This is repeated until the object is completed. This is the oldest of the 3-D printing technologies, first described in 1986, and is still the fastest way to print an object.

On the other hand, in inkjet based printing or powder bed printing, the movable head dispenses a bit of liquid binder onto a bed of powder build material. With light, the binder locks the build powder at that point to the layer below it. The table is then lowered, a new layer of powder material is laid down, and the computer design guides the head to dispense binder at the correct points.

Inkjet 3-D printing is similar to sterolithography, but the
build material is not liquid and the binding comes from the
print head, not from a laser or UV light.
In fused deposition modeling, liquefied build material is laid down and fused together by UV radiation or laser. What is interesting about this (and some other) methods is that you can use several different materials (metal plastic, different colors) in one build.

With fused deposition, you can easily include support material to build up columns for parts of the object that would otherwise be unsupported in the manufacturing process. Now the cool part – the build material can be metal or plastic or glass, while the support material can be something water soluble.

When your build is finished, you can throw it in some water and the supports will disappear, leaving only your desired product. In sterolithography, the support columns are made of the same material as the product, so they have to be cut away.

Fused deposition printing can use different materials for
supports and products. The material is liquefied in the
head before it is deposited.

Finally, there is selective laser sintering. This technique uses powdered metal or plastic. As in stereolithography, a thin layer is spread over the build surface and a laser is used. However, in this case the laser sinters the pieces together, compressing them with heat and pressure into a solid – but not to the point of melting them.

NASA did its first additive manufacturing in space in November of 2014. The International Space Station just got its first 3-D printer. In a small bit of irony, the part they manufactured was a replacement part of the printer itself. The ISS has a fused deposition modeling printer, so our replicator in space may descend from this technology.

Also ironic, the first printed part couldn’t be separated from the build tray. The binder apparently works better in microgravity, so it fused too well with the platform on which the part was built. There’s always a learning curve.

Sintering is just another way to bind the material
particle together.
The original replicator was for making food, and NASA is working on to this as well. There are 3-D printers on the market today that will print food for you. NASA has funded a small business grant to look into the possibility of printing food for long space trips.

Printing food is in some ways very similar – chocolate bunnies or pasta shapes are easy, but it can get more elaborate. Nature Machines has a product called the Foodini that can print burgers, pizza, etc. The technology is similar to other printers, except that the temperatures and textures are different for each ingredient and they have trouble getting many things to hold a 3-D shape against gravity.

The food binder technology is a bit behind – strong enough to hold but edible, and something that will match the flavor, texture, and consistency that one would expect from a certain food. We are actually doing better with medical uses than we are with food.

The software used to design printed objects can be fused to MRI, CT scan or X-ray information to help design very accurate stents, casts, valves, and other plastic or biocompatible material parts to be used in or on the human body. Heart valves are especially useful. A 2015 paper explains printing of metal/glass scaffolds to repair skull defects. Another use described in a 2015 study is for on demand printing of surgical gear needed in war zones.

One possible method to bioprint a vessel. Lay down cells specifically
within an agarose mold. Let them solidify for a time, then put
them in a bioreactor containing growth factors and mild
electrical stimulation so the muscle cells in the walls of
the vessel can mature.
Here's we can go Star Trek one better, 3-D printers are also being used to print living tissues and pretty soon, organs.  3-D bioprinting uses biochemicals and different cell types to build 3-D tissues of various types. A 2014 review explains in common terms the promise and problems with 3-D printing tissues and organs.

One of the problems that must be overcome before organ bioprinting can be realized is the vasculature. For a tissue or organ to survive, it must have a blood supply. This is harder to print because it means having a tubular structure within a solid organ. See the TED video below about printing kidneys.

A new study might have the answer. Using a two print process, the tubular structure is printed using endothelium, muscle in hydrogel tube supports, and then the tissue is printed around it. This must be accomplished before we can take the next step, in vivo bioprinting. In this technique, bioprinting will occur right in or on the human body. That smells a lot like the digital regenerator in The Next Generation. Yes, NASA is funding studies to produce a “bioreplicator” as well.

Next week, let’s tackle a primarily medical device, the tricorder. Think hard about it this week, a workable version might be worth 10 million dollars to you.

Contributed by Mark E. Lasbury, MS, MSEd, PhD

click here if link on video doesn't work

Yu, A., & Khan, M. (2015). On-demand three-dimensional printing of surgical supplies in conflict zones Journal of Trauma and Acute Care Surgery, 78 (1), 201-203 DOI: 10.1097/TA.0000000000000481

Murphy, S., & Atala, A. (2014). 3D bioprinting of tissues and organs Nature Biotechnology, 32 (8), 773-785 DOI: 10.1038/nbt.2958

Kolesky, D., Truby, R., Gladman, A., Busbee, T., Homan, K., & Lewis, J. (2014). Bioprinting: 3D Bioprinting of Vascularized, Heterogeneous Cell-Laden Tissue Constructs (Adv. Mater. 19/2014) Advanced Materials, 26 (19), 2966-2966 DOI: 10.1002/adma.201470124

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