A study done by Julia et al. proved the possibility of using multi-material direct ink printing (4D printing) technology to integrate magnetic nanoparticles with hydrogels. The contactless in-air control of motions like rolling, jumping, and bending is realised because of the interactions between magnetic and nonmagnetic hydrogels. The programmability of patterns of the multi-material also enables its future potential in soft robotics
Starfish 3D printed responsive hydrogels by Dr Ali Mohammed:
Image of Starfish shaped responsive Hydrogel reporoduced with permission from Dr Ali Mohammed
Another fantastic work of 3D printed responsive hydrogels by Dr Ali Mohammed!
The superparamagnetic starfish-shaped hydrogel can be used for magnetically simulated soft robotics and actuators.
Check out the videos to see the 3D printed ‘starfish’ moving responsively to the magnet:
This post was written by Esperanza Shi as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Esperanza is researching the Optimisation of Scanning Strategies for 3D Printed Artificial Joints at Imperial College London, UK.
Turbine-like object printed by 5-axis 3d printing [1]
To improve the quality of printed overhanging structures and surfaces, to reduce the waste of materials of support structures and to reduce the printing time, 3D printers are ready to evolve into multi-axis. Freddie Hong, a PhD candidate at Imperial College London, has been designing 5-axis 3D printers and conformal slicing in an accessible and cheap way to bring these advantages to more individuals. With the rotating printing platform and the slicer designed for 5-axis 3D printers, the overhanging structures can be printed conformally, resulting in reinforced structural strengths.
Visit the video below to watch Freddie sharing more details!
Freddie made the hardware and software kits of open5x open resource, so check out the GitHub and upgrade your desktop 3D printer!
[1] Hong, Freddie, et al. “Open5x: Accessible 5-axis 3D printing and conformal slicing.” CHI Conference on Human Factors in Computing Systems Extended Abstracts. 2022.
This post was written by Esperanza Shi as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Esperanza is researching the Optimisation of Scanning Strategies for 3D Printed Artificial Joints at Imperial College London, UK.
Breaking news from Imperial College London and Empa Switzerland that the research of flying 3D printers is featured as the cover of Nature (Volume 609 Issue 7928, 22 September 2022). Instead of sitting statically on the table like most 3d printers, this aerial robotic 3d printer prints structures in-flight, inspired by natural builders like wasps and bees.
The ‘ScanDrones’ work in pairs with the ‘BuildDrones’ enabling the monitoring of the print quality, thanks to a generic real-time model-predictive-control scheme. Flying 3D printers have been proven to have the potential in conducting constructions post-disaster or in places that are difficult to access. Check out the video produced by the Imperial and Empa researchers below:
Visit the website and original paper below to find out more!
Zhang, Ketao, et al. “Aerial additive manufacturing with multiple autonomous robots.” Nature 609.7928 (2022): 709-717.
This post was written by Esperanza Shi as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Esperanza is researching the Optimisation of Scanning Strategies for 3D Printed Artificial Joints at Imperial College London, UK.
Having been asked this question several times when I was trying to introduce myself and what I do with my PhD to someone I just met, I feel it’s time to update the general public on how cutting-edge research about this technology is looking like now. The fact is that the public no longer views 3D printing as ‘cutting-edge’ because 3D printing technology came out decades ago and has become so easy to access (you can easily buy one desktop 3D printer and set it up at home).
However, 3D printing is not just about the desktop 3D printer you can have at home that extrudes plastics. Just have a glance at this map, and you will understand that 3D printing is such a broad concept and there is much more it’s capable of.
Picture by Dr Usman Waheed
There’re so many aspects we can improve under each category to make the technology better, meanwhile, engineers and scientists never stopped exploring the potential and broadening the horizon of 3D printing. The map or we can say the world of 3D printing is still getting bigger and better, so we DO need PhDs in 3D printing!
I’m not saying this because I’m trying to defend myself as personally being a PhD in 3D printing. The 3 amazing examples I’m going to show you over the next two weeks are to convince you that we DO need PhDs in 3D printing.
This post was written by Esperanza Shi as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Esperanza is researching the Optimisation of Scanning Strategies for 3D Printed Artificial Joints at Imperial College London, UK.
About a year ago, to pursue my academic career I moved from Italy to Sweden, specifically to Uppsala, a lovely town near Stockholm. I am now a PhD student in the local university and in some way I feel that my undergraduate days are well behind me. But you know, Uppsala is a very special city full of students from all around the world who certainly “rule” the town. Here, even if you are no longer a student, you can easily feel like one again just walking into a specific neighborhood at a specific time of the day… Or should I say night?
This neighborhood is called Flogsta, it is located in the west part of the city and most of its inhabitants (basically everyone) are students at Uppsala University. But what’s special about this place you might ask? There, every evening at about 10 p.m. the “Flogsta Scream” can be heard. If you’re from Uppsala you will surely be familiar with this particular “ritual”, or at least have heard of it. Literally. If instead you don’t know anything about it, the Flogsta Scream is (as the name suggest) a scream, but it’s also something more than that. It is a collective act in which students scream together from windows, balconies and rooftops. According to the student population, this act is a kind of “safety valve” or “a cry of anguish” over the accumulated stress of the demands of college life.
Truth be told, it is just an occasion to socialize and make some noise together, but for Uppsala students it is something that you can count on every single day. Sometimes everyone need to scream a little in life, might as well do it the Uppsala way.
This article was written by Niccoló De Berardinis as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Niccoló is researching Bioimaging of biomaterials and biological characterization of 3D-printed alloys for reconstructive surgery at Uppsala University, Sweden.
From the 4th to the 8th of September the European Society of Biomaterials (ESB) hosted its 32nd conference at Palais des Congrès, in Bordeaux, France. ESRs André Plath (ETH Zürich) and Giulio Cavaliere (U. Uppsala) presented some of their current results in poster format during the conference.
“The conference was a great opportunity for networking and building a strong basis for future collaborations. The plenary talks were not only inspiring but represented the top-notch science being developed right now. It was also great to see a good mixture of academics and industries. I commend the ESB for also organizing lunches and talks with senior researchers, industrials, and editors.” says André.
”We met plenty of people working on similar projects and it was a great context to exchange ideas and get insightful feedbacks on my work. Being my first conference I also learnt a lot of useful skills on how to present my research. A lot of the plenary talks were more focus on tissues engineering so it was a good opportunity to expand my knowledge outside my research field” says Giulio
This article was written by André Plath and Giulio Cavaliere as part of a series articles curated by BioTrib’s Early Stage Researchers.
André is one of BioTrib’s Early Stage Researcher‘s who is investigating Boundary Lubrication of Fibrous Scaffolds at ETH Zürich, Switzerland.
Giulio Cavaliere is investigating Additively manufactured biodegradable alloys for bone replacement at Uppsala University, Sweden.
Earlier this year, I took a course titled “Research Introduction for New Ph.D. Students” at Uppsala University. In this course, I was informed of a main task of a university that may often be overlooked. I believe that most people know that two of the primary purposes of a university are education and research. However, there is another significant part of a university’s responsibility, and that is outreach. Universities conduct outreach activities to communicate their research activities to the broader public, especially those outside the academic community. Aside from increasing the general public’s interest in science and technology, a good outreach program may also be a platform for the long-term recruitment of students and researchers.
SciFest Uppsala Logo, taken from SLU website [2]There are many outreach programs here at Uppsala, such as the annual SciFest arranged by Uppsala University and the Swedish University of Agricultural Sciences. From its website, SciFest is a “…festival with a wide range of workshops, shows, competitions, research meetings, and lectures”. This festival has activities for anyone, from kids to adults. Always attended by exhibitors from academia, government authorities, and technology companies, anyone who comes to SciFest will be sure to get a taste of research and science from different perspectives.
As university employees, BioTrib early-stage researchers are also responsible for conducting outreach activity. An outreach program does not have to be a festival, a workshop, or even anything physical. I think the BioTrib’s blog initiative is a good outreach program. With this blog, researchers affiliated with BioTrib can share snippets of our research and even issues within the academic communities to a broader audience. This is especially important for us as BioTrib’s research may significantly impact the medical world in the long term. I hope you’ve found our posts to be interesting and informative!
This article was written by Vidhiaza Leviandhika as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Vidhiaza is researching the Development of Development of 3D-printed gradient alloys for joint implant component at Uppsala University, Sweden
Titanium and its alloys are essential engineering materials. Owing to their fantastic combination of mechanical properties, they can be found in a variety of applications, such as jet engine blades and golf club heads. They are also valuable biomaterials due to their excellent corrosion resistance and biocompatibility. In the biomedical industry, titanium alloys found use in implant devices, for example, dental implants and the stem of a hip replacement. It is no wonder that they are called wonder material. Though their strength is many, titanium and its alloys’ use are still limited due to its apparent weakness, namely, its tribological properties. This means titanium alloys are not ideal in applications where they are in moving contact with another material/component.
Titanium’s poor wear characteristics have been well documented for decades. Among the many explanations, the three highly cited reasons for titanium’s poor tribological properties are [1]:
1. Low work-hardening capability
2. Insufficient protective capability from their tribo-oxides
In the biomedical industry, this means titanium and its alloys are not the best materials to use in joint replacement. In fact, titanium is an inferior material to cobalt-chromium alloys simply because titanium has a more damaging effect on the plastic liner of a joint component, which results in a lower life of the joint replacement as a whole [2].
Currently, there are many research studies that try to improve the wear characteristics of titanium. Naturally, many of those are focused on improving the surface of the material since the wear is a surface phenomenon. The advancement of metal additive manufacturing may also pave the way for more opportunities to improve the wear characteristics of titanium. Indeed, this is also my personal research focus. With the many controllable parameters in additive manufacturing, e.g., scanning strategies, laser parameters, and powder composition, I hope to manufacture a better titanium surface that will be more appropriate for tribological properties. When I achieve that, you’ll be sure to hear it in BioTrib’s blog!
References:
[1] X. X. Li, Q. Y. Zhang, Y. Zhou, J. Q. Liu, K. M. Chen, and S. Q. Wang, “Mild and Severe Wear of Titanium Alloys,” Tribol. Lett., vol. 61, no. 2, p. 14, Feb. 2016, doi: 10.1007/s11249-015-0637-8.
[2] M. Long and H. J. Rack, “Titanium alloys in total joint replacement—a materials science perspective,” Biomaterials, vol. 19, no. 18, pp. 1621–1639, Sep. 1998, doi: 10.1016/S0142-9612(97)00146-4.
This article was written by Vidhiaza Leviandhika as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Vidhiaza is researching the Development of Development of 3D-printed gradient alloys for joint implant component at Uppsala University, Sweden
In May 2022, around 2,000 business leaders and politicians have been in Davos, in Switzerland, for the World Economic Forum’s (WEF) annual meeting. The WEF is an international non-governmental and lobbying organization based in Cologny, canton of Geneva, Switzerland. With the mission to “improve the state of the world by engaging business, political, academic, and other leaders of society to shape global, regional, and industry agendas”, it was founded in 1971 by German engineer and economist Klaus Schwab. The WEF is mostly known for its annual meeting in Davos. Over the course of five days, 3,000 paying members and selected participants – including investors, business leaders, politicians, economists, celebrities, and journalists – discuss global issues.
During the WEF Annual Meeting 2022, ETH Zurich hosts several exclusive events in its RETHINKING LIVING Pavilion. RETHINKING LIVING, created in the spirit of ETH alumnus A. Einstein: ”The important thing is not to stop questioning”, brings together scientists, industry experts, and outstanding global thinkers from ETH Zurich and across the world with the aim to re-think different conceptions of living, re-evaluate life choices, and re-consider the changes needed in a post-pandemic world. Will new technologies build a more sustainable, resilient, and equitable world? On the occasion of the WEF Annual Meeting and to incite exchange, three pioneering exhibits explore the human coexistence in different dimensions: the physical, “White Tower”, the cyber-physical, ”no1s1″ house, and the completely virtual, ”Digital Einstein”.
The White Tower (Cultural site and highest 3d printed building – see header image, credit to Hansmeyer/Dillenburger).
The White Tower is a 29-meter tall, entirely 3D printed building located along the Julier mountain pass in the remote Swiss village of Mulegns. The tower offers exhibitions, performances, and music. It aims to revitalize a village in decline and to describe the rich cultural history of Mulegns and its surroundings. A large portion of the tower will be built in an on-site fabrication lab. In this way, the tower provides digital skills to the mountain regions and advances local trade. It serves as a demonstration of the groundbreaking possibilities of computational design and digital fabrication, which will fundamentally change conventional buildings in the years to come.
No1s1 (no-one’s-one) rethinks collective goods and ownership. It is the first house on the blockchain that can be used by anyone but it belongs to no one. It runs itself and rents itself out. This concept of self-ownership aims to create a digital ecosystem of people, and artificial things. The prototype is a meditation cabin that disattends the usual economic and social expectations. It is decorated with LED lights, connected to a solar panel, and has comfortable seats for meditation inside. No1s1 aims to become an alternative model for real estate and infrastructure.
No1s1 Digital House. Credit Hongyang Wang
The final idea is a “Nature 2.0’’’, a self-sustaining human infrastructure that manages and regulates itself like a natural ecosystem. To celebrate the 100 years of Einstein’s Nobel Prize in Physics, ETH Zurich brings its most famous alumnus to life as an animated character. The implemented platform offers an opportunity to interact with a digital Einstein.
Albert Einstein studied at ETH Zurich between 1896 and 1900, graduating with a diploma in mathematics and natural sciences, and afterward obtained his doctorate at the University of Zurich. After some time in Bern, Einstein returned to his alma mater as a professor of theoretical physics between 1912 and 1914. In the interactive platform, a digital Einstein talks about his years in Zurich. The project is part of the university’s strategy to boost dialogue with society and to bring young people closer to science. Digital Einstein will be taking up his post at various locations around ETH and, eventually, abroad.
Nature 2.0 – brining Einstein to life. Credit: ETH Zurich / Nicole Davidson
This article was written by Elisa Bissacco as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Header Image: Schematic representation of scaffolds characterized by three different lay-down patterns. (a) 0◦/90◦. (b) 0◦/60◦/120◦. (c) 0◦/45◦/90◦/135◦. [1]
The main objective of 3D bioprinting is to recreate human tissues with the same mechanical, structural and biological properties as the corresponding native tissue, in order to solve the problems associated with conventional transplantation techniques (donor site morbidity, organ shortage, etc.). For this purpose, different cell types combined with different biomaterials have been bioprinted according to specific models, but obtaining a 3D scaffold with the desired properties remains a challenge.
The advantage of 3D bioprinting over conventional scaffold fabrication techniques is the ability to control the 3D architecture of scaffolds through parameters such as pore size and geometry. Pore size and shape influence the resulting mechanical properties as well as cell behavior and tissue growth over time. Domingos et al. showed that for a lay down pattern of 0◦/90◦ (filament orientation between layers) with different pore sizes, poly(ε-caprolactone) scaffolds with smaller pores exhibit significantly higher stiffness under compressive conditions, which is an important property in applications such as bone tissue engineering. For different pore shapes with the following lay down pattern: 0◦/90◦, 0◦/60◦/120◦ and 0◦/45◦/90◦/135◦ (see figure) and the same porosity, the increasing number of angles between the filaments of the different layers leads to an increase in the deformability of the construct under compressive conditions.
Regarding the influence of architecture on cell behavior, viability and proliferation of human mesenchymal stem cells (hMSCs) were studied for 21 days and showed that larger pores with a lay down pattern of 0◦/90◦ improve viability and proliferation.
References
[1] Domingos, M., et al. “THE FIRST SYSTEMATIC ANALYSIS OF 3D RAPID PROTOTYPED POLY (e-CAPROLACTONE) SCAFFOLDS MANUFACTURED THROUGH BIOCELL PRINTING: EFFECT OF PORE SIZE AND GEOMETRY ON COMPRESSIVE MECHANICAL BEHAVIOR AND IN VITRO HMSC VIABILITY.” 1758-5082 5 (2013).
This article was written by Marie Moulin as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Marie is researching the Bioprinting of Bone and Cartilage at Uppsala University, Sweden.
On September 1st 2022, at the University of Leeds, we had the honour to attend a presentation from Dr Paul Bills, reader of the BioMetrology group at the University of Huddersfield and co-investigator in the EPSRC Future Metrology Hub. His lecture – titled “Challenges in medical device development: using metrology to unlock the answers” – tackled significant aspects of advanced metrology tools that help assess personalised medical devices. This is of great relevance due to the current paradigm shift in the fabrication of these high-added value components via incorporating additive manufacturing (AM) in their production chain.
Watch Paul Bills leacture on the Challenges in medical device development: using metrology to unlock the answers below:
Dr Bills lecture went beyond the usual citation of the well-known advantages of AM in the orthopaedic field (e.g., high degree of customisation, sustainability, short lead time). One interesting topic that was discussed regarded the current gap in the literature regarding the interplay between osseointegration and infection in additively manufactured orthopaedic porous implants. These AM trabecular-like structures need further microbiological testing because they might be potential sites for deep and late infection. Furthermore, the lack of specification for components conceived by AM which possess an intricate geometry is another challenge yet to be overcome. In-situ metrology techniques could be employed to address that issue. In short, even though many advancements have been made in understanding the behaviour of AM orthopaedic implants, there is still a lot to be discovered from a metrology point of view. Understanding these will be important in ensuring the reliability of the technology for the production of implants in the orthopaedic field.
This post was written by Pedro Luiz Lima dos Santos as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Pedro is researching the Functional Biotribology of the Surface Engineering of 3D Printed Components at the University of Leeds, UK.
While Europe deals with severe drought ‘thought to be one of the worst ever witnessed in the continent’, another country in Asia is dealing with the other side of the spectrum. Pakistan, a South Asian country having an area roughly equivalent to combined total of Germany and France and home to the fifth largest population in the world, has been flooded with excessive rains, the worst in the country’s history. A country whose rainfall average is barely 200 mm in a good year has seen rainfalls of more than 800 mm this year on average and above 1000 mm in some regions, resulting in uncontrollable urban and flash floods, landslides, across the country. More than 60% of the country, equivalent to the total area of the UK, is under water at the moment of writing this post, 1,000+ people have lost their lives while the survivors struggle to feed their families and cattle as most of the agrarian land has been lost[1].
Left: Image of Pakistan taken on August 28 last year. Right: Image of Pakistan taken on August 28 this year with NASA’s MODIS satellite sensor
A country that is home to Himalayas and to ~7.500 glaciers, more than anywhere in the world outside of the polar regions has been facing severe climate change over the past few years. I remember growing up in Pakistan through the 90s and 2000’s. Over the years, the climate has significantly changed for worse, I have seen air conditioning moving from luxury to a necessity. Just in the month of April/May this year when a European starts to get in summer spirits, Pakistan was already witnessing temperatures ranging above 50°C, highest in the world for those months. Pakistan only contributes 0.5% to global carbon emissions yet it is the country predicted to lose all the glaciers and henceforth water supplies first.
As researchers we must not sit idle and await the eventual doom, rather it is our duty to rise up to the occasion and raise our voice / come up with solution to deal with climate crisis. A successful public awareness and collaboration campaign similar to ozone layer depletion campaign[2] is the need of the hour to push back on anti-climate change narrative, raise awareness in the general populace and develop global policy to contain the effects.
This article was written by Sallar Ali Qazi as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Sallar Ali Qazi is researching Mechanical and Tribo-Chemical Wear Modelling of Artificial Joint Prostheses at Imperial College London, UK
Header image: schematic of a polymer brush interface.
Polyelectrolytes are charged polymers with special hydration properties. They are present in our bodies as sulfated glycosaminoglycans (e.g., chondroitin sulfate) and play an important role in lubrication and tissue homeostasis. Tissue engineering novelties are trying to bring the best out of the synthetic world, by mimicking the special properties of these electrolytes, grafted to all kinds of materials [1].
Kwon and Gong [2] studied the effect of negatively charged biomimetic polyelectrolytes for multiple applications, including low friction. Pavoor et al. [1] show the effects of the friction of grafting negatively poly(acrylic acid) and positively charged poly(allylamine hydrochloride) on ultra-high molecular weight polyethylene. Qin et al. [3] showed that the polydopamine-assisted immobilization of chitosan (net positive charge) can improve the biocompatibility and tribological properties of Cobalt Cromium implants. They demonstrated a tenfold decrease in the coefficient of friction upon brush-grafting.
This article was written by André Plath as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
André is researching Boundary Lubrication of Fibrous Scaffolds at ETH Zürich, Switzerland.
References
[1] P.V. Pavoor, B.P. Gearing, O. Muratoglu, R.E. Cohen, A. Bellare, Wear reduction of orthopaedic bearing surfaces using polyelectrolyte multilayer nanocoatings, Biomaterials. 27 (2006) 1527–1533. https://doi.org/10.1016/j.biomaterials.2005.08.022.
[2] H.J. Kwon, J.P. Gong, Negatively charged polyelectrolyte gels as bio-tissue model system and for biomedical application, Current Opinion in Colloid & Interface Science. 11 (2006) 345–350. https://doi.org/10.1016/j.cocis.2006.09.006.
[3] L. Qin, H. Sun, M. Hafezi, Y. Zhang, Polydopamine-Assisted Immobilization of Chitosan Brushes on a Textured CoCrMo Alloy to Improve its Tribology and Biocompatibility, Materials. 12 (2019) 3014. https://doi.org/10.3390/ma12183014.
Total hip arthroplasty (THA) or total hip replacement is one of the most cost effective and reliable surgical operation. This operation consists in replacing the hip joint by prosthetic components allowing the patient suffering from hip pathology (ex: osteoarthritis) to restore painless motion and improve quality of life. For this surgical procedure, different models of implants are available (materials, shape, size and fixation methods) and surgeons decide depending on the age, pathology and medical history of the patient which implant characteristics would suit best. Joint implants are made to stay viable for the longest time possible in the body without revision surgery (second surgery related to an earlier inserted hip prosthesis). Revision surgery can occur after different complications like: repeated dislocation, infection or loosening of the implant and periprosthetic fracture [1].
In order to identify factor contributing to revision surgery and improve surgery procedure, national patient registries have been used in several countries. In 1979, Sweden was the first country to establish a national quality register collecting data on hip arthroplasty: the Swedish Hip Arthroplasty Register (SHAR). Nowadays a lot of countries possess regional and or national Hip Arthroplasty registers like Finland (1980), Norway (1989), Denmark (1995), Australia (1999), England, Wales, Northern Ireland and the Isle of Man (2002). The main objective is to centralize information within the country to follow the evolution of the number of total hip surgery, revision surgery as well as the prevalence in certain age group. Indeed, annual report are published to summarize data collected.
More importantly, registries are used to collect data on the patient, the surgical procedure and operation outcomes. The principal advantage is the possibility to investigate adverse outcomes of primary THA leading to revision surgery and improve surgical procedure. National registries play a major role in documenting the quality of THA to describe best practices and report outlier implants [2]. The 2019 Swedish Hip Arthroplasty Register report mention that “Never have so many hip arthroplasties been undertaken and never have so many research papers using data from the register been published during one operational year” [3].
References
[1] Varacallo M, Luo TD, Johanson NA. Total Hip Arthroplasty Techniques. 2022 Jul 4. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan. [2] Varnum C, Pedersen AB, Rolfson O, Rogmark C, Furnes O, Hallan G, Mäkelä K, de Steiger R, Porter M, Overgaard S. Impact of hip arthroplasty registers on orthopaedic practice and perspectives for the future. EFORT Open Rev. 2019 Jun; 4(6):368-376. doi: 10.1302/2058-5241.4.180091. [3] Kärrholm J, Rogmark C, Naucler E, Nåtman J, Vinblad J, Mohaddes M, Rolfson O. Swedish Hip Arthroplasty Register Annual report 2019. 2021 Feb. doi: 10.18158/H1BdmrOWu.
This article was written by Marie Moulin as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Marie is researching the Bioprinting of Bone and Cartilage at Uppsala University, Sweden.
Stratasys Ltd. introduced and commercialized fused filament fabrication (FFF) in 1989, under the patent name of fused deposition modelling (FDM). In this technique, the polymer/polymer composites filament are extruded from the nozzle head and then the melted polymer is deposited layer by layer to create the final product. Polycarbonate (PC), polylactic acid (PLA), and acrylonitrile butadiene styrene (ABS) are the most commonly used thermoplastics for FDM. It is also compatible with PP, PVA, and bio-compatible PEEK. FDM is by far the most popular 3D printing method, accounting for more than 41.5 percent of the market (2010) [1]
The main defects found in FDM printed parts are void formation and geometrical deformation. Poor interlayer bonding caused by a difference in cooling rate has a negative impact on material quality. Interlayer bonding was improved in a recent study with CF/PEEK printing [2] when a high chamber environment was provided, which reduced the stress acting between the layers. Figure 1 depicts the temperature distribution of the printed parts after printing at various chamber temperatures; uniform temperature distribution was achieved at 230oC. This allows the heat from the top layer, which was recently deposited through the nozzle at high temperatures, to dissipate, gradually eliminating structural imperfections. The thickness of primary and secondary crystals increases as chamber temperature rises, positively impacting the structural and mechanical properties of the printed parts. This has the added benefit of reducing shrinkage and warpage, which are other common issues with FDM printing.
In addition to the chamber temperature, numerous other parameters must be controlled, including nozzle temperature, print speed, layer thickness, infill density, infill pattern, raster angle, and so on, all of which have an impact on the surface and bulk properties of the printed parts.
Header Image: Heat distribution detected for different chamber temperature [2]
This article was written by Dilesh Raj Shrestha as part of an ongoing series of scientific communications written and curated by BioTrib’s Early Stage Researchers.
Dilesh is researching the Development of 3D-printable, self-lubricated polymer composites with improved wear resistance for total joint replacement at Luleå University of Technology, Sweden.
References:
[1] P. Parandoush and D. Lin, “A review on additive manufacturing of polymer-fiber composites,” Composite Structures, vol. 182, pp. 36–53, Dec. 2017, doi: 10.1016/J.COMPSTRUCT.2017.08.088.
[2] K. Rodzeń, E. Harkin-Jones, M. Wegrzyn, P. K. Sharma, and A. Zhigunov, “Improvement of the layer-layer adhesion in FFF 3D printed PEEK/carbon fibre composites,” Composites Part A: Applied Science and Manufacturing, vol. 149, p. 106532, Oct. 2021, doi: 10.1016/J.COMPOSITESA.2021.106532.
