Researchers at Otago Christchurch University 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 says their ultra-portable printer is capable of polymerizing cell-laden bio-inks into “sophisticated tissue analogues.” Scientists even created a companion app, which allows users to 3D scan wounds and deploy the resulting data to create patient-specific tissues on demand, giving the machine clinical end-use potential. .

“[Our system] has multiple applications, including 3D printing of tissues for possible implantation and regeneration, in situ printing and direct wound printing in combination with our scanner application, ”explained Yu Shrike Zhang, the one of the study’s authors. “These are just a few possibilities, but there could be many more in the future.”

The researchers say their smartphone-powered system has potential in situ 3D bioprinting capabilities. Image via the journal Advanced Materials.

Pocket-sized DLP printing

3D bioprinting is increasingly seen in the industry as a potentially lucrative business opportunity, but many machines themselves have a large footprint. While this may be ideal for researchers looking to expand their experiments, it can be a limiting factor when it comes to adopting bio-printers in resource-constrained or point-of-care environments like hospitals or hospitals. surgeries.

Scientists say the lack of accessible 3D bioprinting software is also a major reason the technology has not been widely adopted. a portable, modular and easy to program system.

To address this perceived need, the team harnessed the computing power and imaging capabilities of modern smartphones, using one as the interface for a tiny DLP 3D printer. Equipped with a mini motor, a platform, a tank, an optical system and a projector, the researcher’s prototype measures only 10 cm x 20 cm x 20 cm, while its tank has an area of ​​3.14 cm2, making the machine small but also scalable if necessary.

For example, the lenses of the system can be swapped to achieve different magnifications and light intensities, while its bowl is adjustable, giving it flexibility over multiple length scales. In theory, the printer works by deflecting the patterns captured via its projector onto an optical mirror, onto a convex lens and into a tank placed at 73mm, curing the materials into preprogrammed shapes.

However, before putting this concept into practice, scientists needed to create an interface for their machine. To achieve this, they developed an “automated control system” or a mobile application, capable of using Bluetooth to send instructions to their printer’s microcontroller. The resulting software even includes model cutting and pattern adjustment functionality, as well as adjustable print settings.

A gif of the researchers' miniature DLP 3D printer in action.
The miniature DLP 3D printer (left) and the researchers’ app (right) in action. Gif via Advanced Materials, EZ Gif.

AM entry at point of service

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 on to more advanced cell-charged structures. In initial testing, the system has demonstrated the ability to produce gyroid shapes with complex internal structures as well as several miniature “monuments”, in times of 9 to 12 minutes, depending on complexity.

Compared to the level of precision achieved by Peopoly’s Moai SLA commercial 3D printer, the models produced by the team’s machine were found to be significantly less accurate, reaching a resolution of around 23 µm. However, the scientists also found that their system was 34 times faster and much cheaper to build, so with further adjustments, they say it retains the potential for a faster, more cost-effective alternative.

After establishing the speed and accuracy of their device, the team finally tested its biocompatibility, depositing a cell-laden PEG in the shapes of the nose, ears, kidneys, heart and brain, before evaluating its capabilities in situ by printing directly onto a piece of porcine muscle, treating a “wound” created by scientists for experimental purposes.

While reproducing the complex external features of the human brain proved difficult for the team’s courageous machine, they managed to heal the ‘wound’ of their test subject, maintaining a cell viability of 98%. . As a result, the researchers considered their system to be “an enabling technology for future bioprinting in vivo”, with its personalized application that makes it a particularly accessible tool for those new to the medical field.

“We reasonably envision the great potential of our smartphone-compatible portable DLP printer in various fields such as medicine, biomedicine, home and education,” the team concluded in their article. “This printer has also proven to be suitable for resource-constrained environments, including using the 3D object scanning application, which minimizes the knowledge required to perform CAD. “

The researchers' 3D printed implant next to a bio-printed specimen in situ.
In testing, the researchers 3D printed an implant and printed it directly onto a pig specimen (pictured). Photos via the journal Advanced Materials.

Smartphone-powered progress

Due to their impressive processing power, modern smartphones are increasingly proving to be an ideal basis for experimental miniature 3D printers. Last year, Lumi Industries launched its smartphone-operated LumiBee, through which it aimed to challenge the manufacturer community to create their own resin machines.

Likewise, in 2016, ONO launched a Kickstarter to fund what it dubbed “the first smartphone 3D printer”, raising more than $ 2.3 million in one month. However, things have since turned south for the project, and earlier this month the company finally unplugged, leaving thousands of backers out of pocket and machine-less.

Elsewhere, smartphones have also been attached to 3D printed medical devices, in order to optimize their performance. A team of Korean scientists has developed a new low-cost adapter that turns phones into tools for diagnosing vocal cord disease, while researchers at RMIT University have 3D printed a clip-on filter, which allows users to use mobile cameras for remote medical examinations.

The researchers’ results are detailed in their article entitled “A portable digital light processing 3D printer compatible with a smartphone”.

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 BF Woodfield, Khoon S. Lim and Yu Shrike Zhang.

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The featured image shows a schematic of the researchers’ smartphone-powered DLP 3D printer. Image via the journal Advanced Materials.

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