Researchers at the University of Otago Christchurch and Harvard Medical School have developed a smartphone-based DLP 3D printer with the aim of improving the accessibility of distributed medical manufacturing.
Using a smartphone-powered projector, the team say that their ultra-portable printer is capable of polymerizing cell-laden bio-inks into “sophisticated tissue analogs.” The scientists have even created an accompanying app, which allows users to 3D scan wounds, and deploy the resulting data to create patient-specific tissues on-demand, lending the machine end-use clinical potential.
“[Our system] has multiple applications, including the 3D printing of tissues for possible implantation and regeneration, in-situ printing, and directly printing onto wounds in combination with our scanner app,” explained Yu Shrike Zhang, one of the study’s authors. “These are only a few possibilities, but there could be many more down the road.”
Pocket-sized DLP printing
3D bioprinting is increasingly being seen within the industry as a potentially lucrative commercial opportunity, but many of the machines themselves have large footprints. While this may be ideal for those researchers seeking to scale their experiments, it can be a limiting factor when it comes to adopting bioprinters within resource-limited or point-of-care settings like hospitals or surgeries.
According to the scientists, a lack of accessible 3D bioprinting software is also one of the main reasons that the technology hasn’t been widely adopted, thus given the growing popularity and adaptability of desktop 3D printers, they say “there’s an urgent need” for a portable, modular and easy-to-program system.
To meet this perceived need, the team has harnessed the computing power and imaging capabilities of modern smartphones, by using one as an interface for a tiny DLP 3D printer. Featuring a mini motor, platform, vat, optical system, and projector, the researcher’s prototype measures just 10 cm x 20 cm x 20 cm, while its vat has an area of 3.14 cm2, making the machine small but also scalable if needed.
For instance, the system’s lenses can be swapped out to achieve different magnifications and light intensities, while its vat is adjustable, providing it with flexibility over multiple length scales. In theory, the printer works by deflecting patterns captured via its projector off an optical mirror, onto a convex lens, and into a vat placed 73 mm away, polymerizing materials into pre-programmed shapes.
However, before putting this concept into practice, the scientists needed to create an interface for their machine. To achieve this, they developed an ‘automated control system’ or mobile app, capable of using Bluetooth to send instructions to their printer’s microcontroller. The resulting software even includes model-slicing and pattern-adjusting functionality, as well as adjustable print parameter settings.
Entering point-of-care AM
In order to assess the full capabilities of their new micro-machine, the researchers first used it to 3D print a Photocentric resin, before moving onto more advanced cell-loaded structures. During initial testing, the system demonstrated the ability to produce gyroid shapes with intricate internal structures as well as several miniature ‘monuments,’ in time frames of 9-12 minutes, depending on complexity.
Compared to the level of accuracy achieved by Peopoly’s commercial Moai SLA 3D printer, the models produced by the team’s machine proved considerably less precise, achieving a resolution of around 23 µm. However, the scientists also found their system to be 34 times faster and much cheaper to build, thus with further tweaking, they say it retains the potential of a more rapid, cost-effective alternative.
Having established the speed and accuracy of their device, the team eventually tested its biocompatibility, depositing a cell-loaded PEG into nose, ear, kidney, heart, and brain shapes, before assessing its in-situ capabilities by printing directly onto a piece of porcine muscle, treating an ‘injury’ created by the scientists for experimental purposes.
While replicating the complex external features of the human brain proved difficult for the team’s plucky machine, it did manage to close their test subject’s ‘wound,’ maintaining cell viability of 98%. As a result, the researchers adjudged their system to be “an enabling technology for future in-vivo bioprinting,” with its custom app making it a particularly accessible tool for medical sector novices.
“We reasonably envision the significant potential of our smartphone-enabled portable DLP printer in various fields such as medicine, biomedicine, home, and education,” concluded the team in their paper. “This printer has also proven to be suitable in resource-limited settings, especially by utilizing the 3D object-scanning app, which minimizes the knowledge required for carrying out CAD.”
Due to their impressive processing power, modern smartphones are increasingly proving to be an ideal basis for experimental miniature 3D printers. Just last year, Lumi Industries launched its smartphone-operated LumiBee, through which it aimed to challenge the maker community to create resin machines of their own.
Likewise, back in 2016, ONO launched a Kickstarter to fund what it dubbed ‘the first smartphone 3D printer,’ raising more than $2.3 million in a month. However, things have since turned south for the project, and earlier this month the firm finally pulled the plug, leaving thousands of backers out of pocket and without a machine.
Elsewhere, smartphones have also been attached to 3D printed medical devices, as a means of optimizing their performance. A team of Korean scientists has developed a novel low-cost adapter that turns phones into vocal cord disease diagnostic tools, while RMIT University researchers have 3D printed a clip-on filter, that enables mobile cameras to be used for remote healthcare check-ups.
The researchers’ findings are detailed in their paper titled “A Smartphone-Enabled Portable Digital Light Processing 3D Printer.”
The study was co-authored by Wanlu Li, Mian Wang, Luis Santiago Mille, Juan Antonio Robledo Lara, Valentín Huerta, Tlalli Uribe Velázquez, Feng Cheng, Hongbin Li, Jiaxing Gong, Terry Ching, Caroline A. Murphy, Ami Lesha, Shabir Hassan, Tim B. F. Woodfield, Khoon S. Lim, and Yu Shrike Zhang.
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Featured image shows a diagram of the researchers’ smartphone-powered DLP 3D printer. Image via the Advanced Materials journal.