3D-Printed Microscopic Particles Could Change Medicine and Electronics

Revolutions in the 3D printing world are happening at a fast pace. Earlier this month, a company in Germany created the Wave House using 3D printing. It is Europe's largest 3D-printed building, measuring 600 sq m (6,600 sq ft), and has an unusual appearance in the manner that it has a wave design that couldn't be realized via conventional construction methods. 3D construction printing technology gave the freedom of design and took about 140 hours.

Just last week, the world's first-ever 3D-printed mosque, spanning an area of 5,600 sqm, opened in Jeddah, Saudi Arabia. It took six months to complete the mosque's construction.

When it comes to 3D printing tech, the Texas-based ICON recently unveiled its robotic-arm-mounted 3D printer called Phoenix. This printer can create multi-storey structures with fully enclosed systems from a low-carbon mixture. At 70 feet tall, Phoenix allows for higher construction (up to 27 feet tall) than ICON's current printer, the Vulcan, which has a gantry system with the chassis closer to the ground. 

The company has also announced the development of a new material mixture called CarbonX, which is “the lowest carbon residential building system ready to be used at scale.” Furthermore, ICON has integrated AI into its systems so that anyone can design 3D-printable home schemas via its Vitruvius platform.

But this is not all. Last month, 3D printing allowed the creation of extremely realistic-looking prosthetic eyes in just 90 minutes, in contrast to the usual 8 hours it takes a skilled technician to produce one manually. Then there is 3D printing of drones, propellants, and explosives. 

3D printing, as we covered above, is clearly advancing at a rapid pace, which makes sense, given that interest in this field is rising tremendously. The growing interest has been due to this technique's ability to make custom shapes and print multiple types of material in one part, saving money and material while being environmentally friendly.

Also called additive manufacturing, 3D printing involves staking a material layer by layer using a printer to build an object. However, it is not without its challenges, especially in terms of limited materials, shaping certain materials, restricted size, design inaccuracies, and more.

So, scientists are working on finding ways to overcome these challenges and make 3D printing even more effective and workable at scale.

Recently, a study devised a new process for 3D printing at the microscale that develops particles, at a rate of up to 1 million every day, in almost any shape for use in manufacturing, medicine, and research. 

3D-printing Microscopic Particles

Published in Nature, the study is called “Roll-to-roll, high-resolution 3D printing of shape-specific particles” and conducted by researchers from Stanford University. 

Those involved in the study include Jason M. Kronenfeld, a Ph.D. Graduate Student from Stanford's Department of Chemistry, while Lukas Rother and Maria T. Dulay both work at the Department of Radiology. Both Max A. Saccone and Joseph M. DeSimone belong to the Department of Radiology as well as the Department of Chemical Engineering.

In the study, the researchers noted how particle fabrication is becoming popular thanks to its diverse applications in microelectronics, abrasives, granular systems, microfluidics, bioengineering, and drug and vaccine delivery.

While these extremely small 3D-printed particles have a wide range of applications, they require precise coordination between stage movement, light delivery, and resin (a highly sticky substance) properties. This makes scalable fabrication of such custom microscale particles difficult to achieve. 

As such, the Stanford researchers introduced a high-resolution 3D printing technique, which is scalable for the fabrication of shape-specific particles. This processing technique, which is based on roll-to-roll continuous liquid interface production (r2rCLIP), is far more efficient at printing huge amounts of customizable and highly detailed microscale particles per day.

According to the study's lead author, Kronenfeld, a Ph.D. candidate in the DeSimone lab, this technique allows more complex shapes to be created at the microscopic scale, out of a wide range of materials, and at speeds that haven't been seen before for particle fabrication. 

The research builds on the printing technique called continuous liquid interface production (CLIP), which was introduced nearly a decade ago, in 2015, by DeSimone and colleagues. 

CLIP uses UV light and projects it in slices to cure resin rapidly into the desired shape. What distinguishes this technique is that above the UV light projector, there is a window that allows oxygen to penetrate. This oxygen-permeable window prevents the liquid resin from sticking to it by creating what's called a “dead zone.” Hence, we are able to cure delicate features without tearing each layer from the window, which results in faster particle printing.

The co-author DeSimone, who's the Sanjiv Sam Gambhir Professor of Translational Medicine at Stanford and has been responsible for various breakthroughs in the fields of medical devices, nanomedicine, and 3D printing, said:

“Using light to fabricate objects without molds opens up a whole new horizon in the particle world.” 

Making it happen at a scalable level can further provide opportunities to use these particulates “to drive the industries of the future,” he added.

Click here to learn what makes 3D printing a potential $500 billion market.

r2rCLIP to Enable Mass Production

Based on CLIP, the researchers created a new process for mass-producing uniquely shaped nanoscale particles. First, they carefully tensioned a film and sent it to the CLIP printer, where hundreds of shapes were printed onto the film at the same time.

Then, it is moved on to washing, curing, and removing the shapes. All of these steps can be customized depending on the material used and the shape involved. The empty film, at last, is rolled back up, hence the name roll-to-roll CLIP, or r2rCLIP. 

The use of single-digit, micron-resolution optics, along with a continuous roll of film instead of a static platform, enabled the researchers to achieve quick permutable fabrication as well as liftoff of particles from different materials and with more intricate geometries. 

As per the study, the geometries included those that couldn't be achieved with advanced mold-based techniques, hence showcasing the unique capabilities of the team's approach.

Both the moldable and non-moldable forms of r2rCLIP were shown with voxel (a single sample on a regularly spaced, 3D grid) sizes of 2.0 × 2.0 µm2 in print and having an unsupported thickness of 1.1 ± 0.3 µm. 

Before roll-to-roll CLIP, a batch of printed particles has to be processed manually, which is a slow process that requires great physical effort. The automation of r2rCLIP now allows for fabrication at an unprecedented level, i.e., up to 1,000,000 particles every single day.

The particle-printing process achieved full automation through the substitution of the CLIP printer's static build plate with a continuous-film, modular, roll-to-roll system. This allows for automated in-line post-processing that includes cleaning, post-curing, and particle liftoff (harvesting). 

In its paper, the team noted that a big advantage of using its roll-to-roll CLIP technique for particle fabrication is its innate moldless process. This enables the production of an extensive range of particle geometries without having to change the layout.

When it comes to particle fabrication, different approaches involve trade-offs between scalability, speed, uniformity, material properties, and geometric control. For example, while some processes can print on the nanometer scale, they tend to be slower. 

“We're navigating a precise balance between speed and resolution,” said Kronenfeld. Their technique, he noted, is “distinctively capable” of manufacturing high-resolution outputs, but it can also preserve the speed needed to meet the particle production volumes required for different applications. 

He added:

“Techniques with potential for translational impact must be feasibly adaptable from the research lab scale to that of industrial production.” 

Vast Applications

The research, which was funded by the National Science Foundation Graduate Research Fellowship Program and the Bill & Melinda Gates Foundation, aims to be widely adopted by other researchers and industry.

With 3D printing evolving rapidly, r2rCLIP here stands as “a foundational technology,” said DeSimone, who's a founding faculty director of Satnford's Center for STEMM Mentorship, co-director of the Canary Center at Stanford for Cancer Early Detection, and a faculty fellow of Sarafan ChEM-H.

However, according to DeSimone, the industry is starting to focus on 3D products rather than these processes, which are “becoming clearly valuable and useful.” So, the question now is: 

“What are the high-value applications?”

As per the study, microscopic particles with intricate designs enable direct integration within analytical, biomedical, and advanced materials applications.

The researchers themselves have been experimenting with the production of both soft and hard particles, made of hydrogels, which can see applications in drug delivery in the body, and ceramics, which can be used in microelectronics manufacturing.

By using them in the production of hydrogel particles, it becomes possible to fill these particles to achieve adjustable, gradient, or pulsatile-release profiles in a singular injection. Many studies previously explored the creation of suitable photopolymer resin systems and examined the influence of materials' shape, size, and biocompatibility on localization and delivery. This led to the creation of bioscaffolds and delivery manifolds, which opened up numerous prospects for fabricating hydrogel particles for drug delivery despite not involving a scalable, permutable fabrication procedure. 

Here, the team fabricated hydrogel cubes of 400 µm unit size and manually filled them with about eight nl of representative cargo post-printing, followed by topping with a hydrogel cap. The study highlighted the potential for a programmable pallet of cargo release through future research by building on previous studies on drug-delivery vehicle kinetics and leveraging the adjustable properties of molecular weight and wall thickness.

The material and mechanical versatility, from ceramic to hydrogel, can also assist in the creation of smart materials. So, by demonstrating fabrication potential over such a wide range, this scalable particle production approach also has potential application in micro tools and electronics, it added. 

The high throughput of the technique (r2rCLIP), meanwhile, has direct implications for industrial-scale production of micro devices such as microrobots and cargo delivery systems. This is particularly supportable for the production of ceramic materials. 

By utilizing preceramic resins to manufacture technical ceramic particles at a mass scale, the study says, it can have possible applications in microelectromechanical systems, mechanical planarization techniques as slurry components, and conductive particles that will allow for industrial applications such as telecommunications and healthcare.

According to Dulay, a senior research scientist:

“There's a wide array of applications, and we're just beginning to explore them. It's quite extraordinary where we're at with this technique.”

Companies Using Innovative Approaches to Additive Manufacturing

Now, let's take a look at a couple of companies that are leading the way in 3D printing:

#1. HP Inc.

A well-known name in the traditional printing industry, HP Inc. has been making a lot of moves in 3D printing, which involves its Multi Jet Fusion (MJF) technology, which is designed for industrial production. It offers high-speed 3D printing and the ability to control the properties of each individual voxel. The company's Jet Fusion for industrial production and prototyping involves 5600 Series to optimize applications for flexible production at scale 1, 5400 Series for quality white applications, 5200 Series to produce high-value final 3D part production, and 4200 to optimize productivity and cost.

This week, HP is planning to display 3D-printed parts leveraging its new material, PA 12 S, at the annual AM Forum Conference in Berlin. The material is custom-made for the company's 3D polymer solutions used in industries and offers benefits like cost reduction and excellent surface aesthetics.

With a market cap of $29.83 bln, the company's shares are trading at $30.66, up 1.1% year-to-date (YTD). The company has posted revenue (TTM) of $53.1 bln, an EPS (TTM) of 3.41, and a P/E (TTM) of 8.91. It pays a dividend yield of 3.62%.

#2. Materialise NV

This Belgian-based company offers a broad range of 3D printing services, including metal and polymer printing. The company is particularly known for its expertise in the healthcare sector, where it uses 3D printing for implants, surgical guides, and anatomical models. 

Late last year, Ricoh, a Japanese imaging and electronics company, partnered with Materialise to bring point-of-care 3D printing to US hospitals, which will enable the production of anatomical models of a patient's anatomy. And last month, Materialise launched a personalized 3D-printed temporomandibular joint (TMJ) treatment.

With a market cap of $293.56 mln, the company's shares are trading at $5.36, down over 24% YTD. The company has posted revenue (TTM) of $278.69 mln, an EPS (TTM) of 0.13, and a P/E (TTM) of 39.57.

Recently, the company announced its financial results for Q4 and the entire 2023, during which its revenue increased by 4.1% to €65.3 million and 10.4% to €256.1 million, respectively, despite the “turbulent macroeconomic and geo-political conditions.”

Materialise also reported €128 million in cash and cash equivalents, which its CEO Brigitte de Vet-Veithen said, along with additional financing secured, makes it “well positioned” to continue offering innovative 3D product and software solutions.

Conclusion

As we noted above, 3D printing has some great benefits in several industries, including medical, automotive, aerospace, consumer goods, jewelry, and defense and military. While it is already seeing growing curiosity and usage, its adoption is only going to grow in the coming years as more research allows for the production of objects at scale. The future of 3D printing is simply bright, showcasing the promise to revolutionize manufacturing and create a more resilient future.