Microscale 3-D Printing

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Inks made from different types of materials, precisely applied, are greatly expanding the kinds of things that can be printed.

Despite the excitement that 3-D printing has generated, its capabilities remain rather limited. It can be used to make complex shapes, but most commonly only out of plastics. Even manufacturers using an advanced version of the technology known as additive manufacturing typically have expanded the material palette only to a few types of metal alloys. But what if 3-D printers could use a wide assortment of different materials, from living cells to semiconductors, mixing and matching the “inks” with precision?

Jennifer Lewis, a materials scientist at Harvard University, is developing the chemistry and machines to make that possible. She prints intricately shaped objects from “the ground up,” precisely adding materials that are useful for their mechanical properties, electrical conductivity, or optical traits. This means 3-D printing technology could make objects that sense and respond to their environment. “Integrating form and function,” she says, “is the next big thing that needs to happen in 3-D printing.”

A group at Princeton University has printed a bionic ear, combining biological tissue and electronics (see “Cyborg Parts”), while a team of researchers at the University of Cambridge has printed retinal cells to form complex eye tissue. But even among these impressive efforts to extend the possibilities of 3-D printing, Lewis’s lab stands out for the range of materials and types of objects it can print.

Last year, Lewis and her students showed they could print the microscopic electrodes and other components needed for tiny lithium-ion batteries (see “Printing Batteries”). Other projects include printed sensors fabricated on plastic patches that athletes could one day wear to detect concussions and measure violent impacts. Most recently, her group printed biological tissue interwoven with a complex network of blood vessels. To do this, the researchers had to make inks out of various types of cells and the materials that form the matrix supporting them. The work addresses one of the lingering challenges in creating artificial organs for drug testing or, someday, for use as replacement parts: how to create a vascular system to keep the cells alive.

Written By: David Rotman
continue to source article at technologyreview.com

15 COMMENTS

  1. This is a good answer to Rod the Farmer’s question about the kinds of material.

    Ultimately, also, there is nothing that stops these technologies combining with photo/e-beam etching, plating and vapour deposition technologies working on complex surfaces.

    The work addresses one of the lingering challenges in creating artificial organs for drug testing or, someday, for use as replacement parts: how to create a vascular system to keep the cells alive.

    This may not only allow existing organs to be duplicated but may also allow totally new organs. A printed vascular system will facilitate the blood sugar fuel cell for pure electronics which can then be used for neural prosthetics and neural pacemakers like those for Parkinsonism, dystonia and epilepsy but also the newly envisaged hippocampal implants to restore memory capability.

    My spies tell me the latest Bluetooth now works reliably. Implanted as another sense organ, if the data is salient enough, I wonder how it will feel? I wonder if people will feel a bit poorly on upgrade Thursday?

    • In reply to #3 by phil rimmer:

      My spies tell me the latest Bluetooth now works reliably. Implanted as another sense organ, if the data is salient enough, I wonder how it will feel? I wonder how poorly people will feel on upgrade Thursday?

      I see Total Recall crossed with The Matrix here, the ability to not only implant memories but to also download vast amounts of information to the implant. If only.

  2. @OP,

    ‘Despite the excitement that 3-D printing has generated, its capabilities remain rather limited. It can be used to make complex shapes, but most commonly only out of plastics.’

    What is so limiting about plastics? Granted that printing in metals and the ability to print electronic components would up the anti somewhat, but the possibilities with plastics alone are only limited by imagination, ones own ability to think in three dimensions and printing resolution.

    I would love to be able to afford one along with a 3D Scanner even if it were to do nothing more than mess around, I find the whole concept fascinating.

    • In reply to #4 by veggiemanuk:

      @OP,

      ‘Despite the excitement that 3-D printing has generated, its capabilities remain rather limited. It can be used to make complex shapes, but most commonly only out of plastics.’

      What is so limiting about plastics?

      The limitation is that not every type of plastic can be melted and squeezed out of a tiny printer nozzle. Some plastics require a specific fabrication method to be of any use (vacuum forming, lamination, extrusions, etc). And we haven’t even breached the subject of composites (fiberglass resin, Kevlar, etc.) which can only be made in steps.

      Sometimes you need to fabricate a metal object from an alloy that has to be impact or stress resistant or have certain thermal properties. Sometimes you just need metal. Try and make a frying pan from a plastic that can be melted…. Or a piston for a gasoline engine… Or a simple drill bit. There are TONS of examples.

      • In reply to #6 by NearlyNakedApe:

        In reply to #4 by veggiemanuk:

        But its not limited to plastics and with plastics its not limited to thermoplastics.

        I’ve worked with ceramic filled materials like these and there are composites like these.

        Sintered printed metal parts can have impressive performances, but the key is re-imagining how to use the available materials.

        I suspect I could make a very high performance drill bit using even the ceramic filled material. It can withstand 200 Celsius, but it it will start to lose strength if it gets too hot, so I can design in at no extra manufacturing cost cooling tubes to carry either pumped coolant or a passive series of heat pipes. I could build a pump in situ within the barrel of the drill and disc heat sinks, the pump effectively powered by the drill rotation and static neodymium magnets on the outside. The profile could be plated for added strength and the cutting surface would be formed by a photo-cured epoxy coat inkjet applied where needed, a dip in diamond powder and a pulse of UV.

        Just imagine bespoke cutting tools, mills and drills with unique profiles.

        We’ll make new stuff not old stuff.

        • In reply to #7 by phil rimmer:

          Sintered printed metal parts can have impressive performances, but the key is re-imagining how to use the available materials.

          Hi Phil!
          Remember this 3D printed rocket engine injector – I linked on an earlier discussion!

          NASA Tests Limits of 3-D Printing with Powerful Rocket Engine Check

          The component was manufactured using selective laser melting. This method built up layers of nickel-chromium alloy powder to make the complex, subscale injector with its 28 elements for channeling and mixing propellants. The part was similar in size to injectors that power small rocket engines. It was similar in design to injectors for large engines, such as the RS-25 engine that will power NASA’s Space Launch System (SLS) rocket for deep space human missions to an asteroid and Mars.

          • In reply to #8 by Alan4discussion:

            In reply to #7 by phil rimmer:

            Sintered printed metal parts can have impressive performances, but the key is re-imagining how to use the available materials.

            Hi Phil!
            Remember this 3D printed rocket engine injector – I linked on an earlier discussion!

            Fabulous illustration, Alan. 115 parts down to two! This is a key factor in improving quality and reliability. Worst case manufacturing considerations are upended entirely.

            Fluid flow requirements can be perfectly modeled these days with FEA software. I can well imagine rocket scientists daydreaming over theoretically perfect designs and continuously changing profiles of channels with rifled flutes and the like optimising combustion and minimising turbulence, but quite beyond manufacture.

            Now, more than ever before, form can be fully at the service of function.

        • In reply to #7 by phil rimmer:

          In reply to #6 by NearlyNakedApe:

          In reply to #4 by veggiemanuk:

          But its not limited to plastics and with plastics its not limited to thermoplastics.

          I’ve worked with ceramic filled materials like these and there are composites like these.

          Sintered printed metal parts can have impressive perform…

          Wow!! Do I stand corrected or what?… I had no idea that 3D printing was at such an advanced stage of technological refinement. I thought 3D printers could only make soft plastic parts. I guess I assumed that the 3D printers currently available to the public was all there was…. Mea culpa. And thanks for the heads-up Phil.

          This is absolutely fascinating stuff. Now about that drill bit…

          I suspect I could make a very high performance drill bit using even the ceramic filled material. It can withstand 200 Celsius, but it will start to lose strength if it gets too hot, so I can design in at no extra manufacturing cost cooling tubes to carry either pumped coolant or a passive series of heat pipes.

          Sure but engineering design whether for tools or electronics or anything else, almost always requires trade-offs. Cooling tubes may help to keep the drill bit’s temperature down but it could reduce its structural strength. I suspect this complex scheme would be effective only in larger diameter drill bits or end mills. For smaller diameter bits, the cooling tubes might be too small to provide any significant cooling. So the smaller bit would probably be cooled more efficiently by using the traditional method of cooling (pouring a constant stream of cutting fluid on the tool and part during machining).

          For the larger bits, a combination of both inner and outer cooling would be ideal. The part being machined will dissipate heat more efficiently from the constant stream of coolant directly at the tool-part interface but also over the entire part.

          But the bottom line is that sophisticated cutting tools (or just about anything) could be fabricated from complex alloys for a fraction of the cost (like rocket engine parts that can withstand 6000 deg F – thanks for the link alan4discussion).

          • In reply to #13 by NearlyNakedApe:

            Your point about materials still stands, of course. At some point the choices of printable materials runs out but as you can see wholly new fabrications conferring strength (as in the bone structure in the other thread with its interior graded foam) and other functionalities are possible and new materials pop up each month.

            I took a plastic drill bit as a bit of a challenge (ouch). It may not be doable…yet. But…

            The drill bit has no need to conform to existing shapes dictated by existing manufacturing methods. The upper stem can be broad comprising a set of disks, inside of which is the armature set of disks, nested. These comprise a Tesla style tangential fluid pump and the outside disk covers constitute the rotating heatsink fins. I’m imagining not the odd tube but a full set of arteries, capilliaries and veins. It may, though, just be easier printing out of one of the tough bronze type materials

            Strength and therefore cutting speed will be a limit with plastic, even plated, but this could be fine for wood, plastic and some metal alloys taken slowly.

            Again you are exactly right on the feasibility of smaller sizes, but metal overprinting on a stronger stock metal core will possibly solve that one.

            My point is only that printed products are best re-imagined to get the most out of them.

            Its all marvelous fun though…

  3. Incidentally one new metal forming 3D fab technology in the works is laser selective electro-plating. Build speeds of 1mm per 40 seconds have been shown. The topical heat of the laser dramatically raises the plating rate (every ten degrees Celsius doubles it), chilling the rest likewise can increase the plating contrast.

  4. A group at Princeton University has printed a bionic ear, combining biological tissue and electronics (see “Cyborg Parts”), while a team of researchers at the University of Cambridge has printed retinal cells to form complex eye tissue. But even among these impressive efforts to extend the possibilities of 3-D printing, Lewis’s lab stands out for the range of materials and types of objects it can print.

    The “Cyborg Parts” link, does not have an image. Nature abhors a vacuum!

    http://ngm.nationalgeographic.com/2011/03/big-idea/organ-regeneration-text
    In the future people who need a body part may get their own back—regrown in the lab from their own cells.

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