3D Printing Tech Digest - February 2017

Nerve damage repaired in thigh of rats

Researchers at Kyoto University have successfully used the Kenzan 3D printing method to implant cells into a rat’s thigh. The Kenzan method involves skewering cells onto individual needles in an array. Over time the cells bond together and are then removed as a whole from the array of needles. The tissue is then put into a bioreactor to ‘self-sort’. This makes it distinct from other methods used in bioprinting which involve printing cells into a bed of hydrogel.

In the Kyoto study rats with thigh nerve damage were divided into two groups, half were given a transplanted silicon tube to enhance nerve regeneration, the other half were given a 3D bio-printed tissue vessel. The bio-printed tissue treated rats showed faster nerve regeneration. The team plan to carry out further studies.  

Organovo prints kidney structure

Organovo, a bio-printing firm, has recently released a research paper and poster  showing the successful printing of veins within a kidney. In the paper Organovo reports the successful binding of kidney cells into a structure of vessels that mimic the natural structure of a proximal tubule (a structure within the kidney which regulates filtrate pH). The team further showed the proof of concept for drug testing by doping the tubule with toxic substances. Lastly the team discovered they could reconstruct a diseased tubular structure by introducing tubulointerstitial fibrosis into the cells. Organovo see this as having uses in assessing human renal toxicity over extended time periods. 

Stretchy printing

Researchers in Singapore and Israel have developed a range of stretchy materials that can be used in vat polymerisation 3D printing. The researchers printed a range of objects to prove the versatility of their material including a Bucky ball (hollow, perforated sphere), a flexible gripper, and a soft actuator. The team demonstrated that the Bucky ball could be used as a conductive switch. The team also used the printed flexible gripper to create a claw-like structure which could, with pneumatic actuation, pick up a small object. The team used a mixture of Allnex EBECRYL resin strains 8413 and 113, and printed it using a Pico Plus39 DLP printer from Asiga. To preserve elasticity, the UV curable resin bath is kept a constant 70 degrees Celsius.

Lens copies the human eye

A team of scientists from the University of Stuttgart, Germany, have recreated the way human eyes focus in cameras. They achieved this by 3D printing four plastic lenses onto a single image sensor. The lenses each had different focal lengths – shorter focal length equals a wider field of view with less clarity, and vice versa with the long focal length lens. Having these variable focal lengths enabled the final device to have great focus in the centre, that blurred as it moved to the periphery. The whole device was less than 300 micrometres square. It is claimed that as only the centre of the image would require intensive processing, less power and processing time would be needed compared with images captured by conventional optics. This approach has possible uses in surgical cameras, or autonomous car vision systems.

Malleable 3D printed objects

MIT chemists have discovered a method to alter 3D printed polymer constructs after the printing process. This means that post printing the structure of the object can be added to, or fused with other similarly printed objects to create more complex structures. The team designed new polymers (called TTC) which contain an organic catalyst that can be activated by blue light causing the polymers to relax, allowing for manipulation. The researchers demonstrated that by incorporating different monomers they can alter the material’s stiffness and hydrophobicity, and control swelling and contraction of the material in reaction to temperature. In addition a monomer can be used to fuse two parts together by shining light onto the contact point, creating a new structure.

Pharmaprinting

Scientists at University College of Los Angeles have created a bioink 3D printed Ropinirole pill (used for treatment of muscle problems in Parkinson’s disease). The team used inkjet 3D printing as it can be performed at room temperature hence avoiding damaging the active ingredient. They used a 3D printable bioink made from hyaluronic acid (commonly found in skin, connective tissue etc.) with an added photoinitiator meaning the ink will solidify when it meets light. To this base the active ingredient is added. The mixture is then printed into pill cases. The deposition of the mixture is regulated through a piezoelectric nozzle. The resulting pill was tested and shown to be effective.

3D printed house

Apis Cor, a San Francisco based 3D printing company, has 3D printed a 400 square foot house 60 miles south of Moscow. The house is constructed of concrete and took a total of 24 hours to construct. It costs USD 10,000. The printer can function at lows of 0 degrees Celsius. However the concrete ‘ink’ cannot, so it was protected from the frigid Russian winter by a tent. 

Holographic 3D Printing technique 

Daqri, a startup making holographic chips, has demonstrated its technology’s ability to 3D print a paperclip in a few seconds. The well-established technique is to use a laser to print an object into a light activated monomer that is then transformed by application of light into a solid plastic. Instead of printing it layer by layer Daqri’s technique does it all simultaneously by utilizing a hologram, or a 3D light field. Daqri’s hologram is created by shining a laser through a silicon wafer of tiny tuneable crystals that control how the laser light behaves and create a hologram. By projecting the hologram onto the light activated monopolymers the area the 3D holographic projection illuminates is solidified in a few seconds. Daqri believes that if the tech is scaled up (using a larger wafer to create more image depth) printing larger objects should take about the same amount of time as printing smaller ones.

Siemens 3D prints gas turbine blade

Siemens, a German engineering company, has tested its 3D printed gas turbine blade. It was tested at 13,000 revolutions per minute and at temperatures of 1250 degrees Celsius. The turbine can withstand such high temperatures because of sophisticated internal geometries offered by 3D printing, allowing for better cooling. The blades made of polycrystalline nickel superalloy powder were manufactured by Material Solutions, a 3D printing company acquired by Siemens in 2016. 

Dental printing gets pushed in Dubai; 3D Systems acquires NextDent brand

At the Arab Health Congress (AHC) in Dubai, Dubai Health Authority (DHA) announced its push to increase the use of 3D printing in dentistry by the end of 2017, according to several news sites. Also at the AHC a deal was made between Middle East Dental Laboratory and 3D printing company Sinterix to produce 3D printed teeth. Sinterix recently fitted a human with a 14-unit metal framework set. Working on dental and oral cavity scans Sinterix can print a set of false teeth within four hours, it claims. 
Also in the dental field, 3D Systems has announced that it has acquired Vertex Global Holding, the parent company of Vertex and NextDent brands. NextDent and Vertex are producers of twelve 3D printing materials suited to dental applications, such as the production of trays, models, drilling templates, dentures, orthodontic splints, crowns and bridges. 

3D printing in F1

Ferrari F1, a Formula 1 racing team, is investing in 3D printing for its 2017 F1 car. Due to advances in the car’s design and power the engine will find itself under greater strain than previously. To help it cope the company is apparently testing a new 3D printed piston design using steel rather than the traditional aluminium (according to a news story in the respected motorsport magazine Autosport). 3D printing has opened the possibility to use steel as a component due to its ability to print weight-reducing honeycomb structures. 

Jet cooling can reduce production time of 3D printing

3D4Makers has developed a method of cooling extruded filament which doesn’t require water – a multiple jet air cooling system. Traditional water cooling methods require post-production processing such as baking to thoroughly remove the water which is added to cool the material and ensure a smooth and even finish. However, by using 3D4Makers’ method production speed is improved, and the company says the filament has better layer adhesion meaning stronger more impact resistant final parts.  

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