When most makers think about 3D printing, we picture parts we can easily hold in our hands: brackets, tools, enclosures, replacement components, or maybe the occasional dragon that takes up an entire build plate.
Microscopic 3D printing operates in a completely different world.
Here, a few microns can determine whether a channel flows correctly, whether two medical components align, or whether a tiny device can perform more than one function inside the body.
In the third and final part of our conversation with Carl Leonard of Boston Micro Fabrication, we talked about how micro 3D printing is affecting medical technology, why materials are just as important as machines, and what the next five to 10 years could look like.
And the biggest takeaway is simple:
Sometimes the smallest printed parts can create the biggest possibilities.
How Smaller Parts Could Improve Patient Outcomes
Carl was careful to make one important distinction: BMF manufactures machines and materials. Medical-device companies use that technology to make components, clinicians use the finished devices, and patients ultimately receive the benefit.
That chain matters because a 3D printer does not improve a patient’s health by itself. What it can do is give engineers new ways to design and manufacture the devices physicians rely on.
At the microscopic scale, that may mean:
- Smaller instruments and incisions
- Less disruption as a device passes through the body
- More sophisticated diagnostic channels inside a single component
- Faster development of new medical technology
- Patient-specific geometries
- More precise methods of localized drug delivery or fluid sampling
Shrinking a medical component is not just about making the same design smaller. As the dimensions decrease, the tolerances, surface finish, material behavior, and manufacturing process all become much more demanding.
That is where micro 3D printing starts to become especially interesting.
A Tiny Device With Two Microscopic Channels
One example Carl discussed focuses around a pair of tiny needles. One side introduces fluid into a localized area of the skin while the other retrieves fluid containing nearby biological markers for analysis.
The 3D-printed component holding those needles required two channels measuring about 100 microns across, separated by roughly 20 to 40 microns.
That is tiny.
More importantly, it is the kind of geometry that could become extremely expensive—or potentially impossible—to develop through conventional tooling, especially when a team is still testing and changing the design.
Micro 3D printing allowed the device developers to create that geometry, iterate on it, and validate that the concept worked without first committing to a complicated traditional manufacturing process.
For makers, the lesson should sound familiar. Rapid prototyping is valuable at any size, but the advantage becomes even greater when the alternative is microscopic tooling with extremely tight tolerances.
The Printer Is Only Half the Story
It is easy to focus on resolution when talking about micro 3D printing. After all, the ability to print extremely small features is what immediately grabs your attention.
But the material has to do the job after the print is finished.
BMF works with several categories of materials, including:
- High-temperature resins
- Low-viscosity materials
- Biocompatible materials for certain medical-device applications
- Ceramic materials
- Optically clear resin
- Soluble resin for sacrificial molds
- Third-party engineering materials adapted to BMF’s machines
Each one brings a different combination of temperature resistance, surface quality, mechanical performance, optical behavior, and biocompatibility.
There is no universal resin that is perfect for every application.
A material that produces a highly accurate part may not have the weatherability, implantability, chemical resistance, or outgassing performance required for the final use. A resin that works beautifully for a prototype might not be the material needed for the finished component.
That limitation led to one of the most fascinating ideas in our conversation: using a 3D print to manufacture a part without making the print itself the final part.
Print the Mold, Then Dissolve It
Imagine trying to print a sphere trapped inside another shape.
The top of that sphere would normally need support, but if the surrounding geometry blocks access, removing those supports may be impossible.
Instead of printing the finished object directly, BMF’s soluble resin can be used to print a sacrificial mold—a negative space that can be filled with another material.
The process works like this:
1. Print the mold in soluble resin.
2. Inject the desired final material into the mold.
3. Allow that material to cure or cool.
4. Place the combined part in BMF's specified 5:95 sodium-hydroxide-to-distilled-water solution, following the manufacturer's handling and safety guidance.
5. Let the printed mold dissolve away.
What remains is the final component, produced in a material that may offer properties the printable resin could not.
That material might be a medical polyurethane, nylon, ABS, or something else chosen for the application.
This approach preserves one of the greatest advantages of micro 3D printing—the ability to create intricate geometry with excellent surface quality—while opening the door to a much broader selection of final materials.
Carl described this as the difference between direct and indirect printing. Direct printing makes the finished component. Indirect printing makes the tool that creates the finished component.
It is essentially a microscopic version of investment casting, and it completely changes how engineers can think about difficult geometries.
Why Optically Clear Resin Is So Difficult
Another major materials challenge is optical clarity.
Many resins used for high-precision printing contain light-absorbing agents. Those absorbers help control how deeply the UV light penetrates the resin, which is critical for maintaining accuracy and preventing unwanted curing.
The downside is color.
A yellow or translucent resin may be perfectly acceptable for a mechanical component, but it can create problems in a microfluidic chip where researchers need to observe cells, droplets, or fluid moving through microscopic channels. Some materials can also produce autofluorescence, adding background noise to optical measurements.
BMF Clear was developed to combine optical transparency with the micron-level accuracy required for those parts. According to BMF, the material provides greater than 90% light transmission and can print at layer heights as small as 10 microns.
Making a clear resin at the macro scale is difficult enough. Doing it at the micro scale means balancing optical transparency, light absorption, curing behavior, surface finish, and dimensional accuracy at the same time.
That is not simply a matter of pouring a different resin into the vat.
The Machine and Material Have to Work Together
BMF’s printers use a process called Projection Micro Stereolithography, or PµSL.
Like other vat-photopolymerization systems, it uses light to cure liquid resin layer by layer. The difference is that the system is engineered around microscopic features, extremely tight tolerances, and fine surface quality.
As the materials change, the hardware has to evolve with them.
Higher-viscosity resins may require changes to material handling. Optically demanding parts depend on precise calibration and controlled exposure. The light engine, motion system, membrane, roller, processing parameters, and resin chemistry all have to work together.
This is one reason material development and machine development cannot be treated as completely separate problems.
From “Can We Print It?” to “Can We Manufacture It?”
The next stage for microscopic 3D printing is not simply producing one impressive part.
It is producing that part accurately and reproducibly, again and again.
As Carl put it, the question is moving from “Can we print it?” to “Can we manufacture it reproducibly?”
Better materials will be a major part of that shift. Carl expects continued demand for materials that are:
- Bioresorbable
- Elastomeric
- Optically functional
- More temperature-resistant
- More chemically resistant
But material development is only one part of the future.
Integration could be just as important.
Today, some microscopic products still require several tiny components to be assembled by hand or with specialized equipment. If engineers can redesign those assemblies as one printable component, they could reduce part counts, eliminate alignment problems, and simplify production.
Assembly can be frustrating at normal scale. At microscopic scale, it becomes a completely different challenge.
Could Hospitals Print Patient-Specific Parts?
Personalization may be the most exciting long-term possibility.
Traditional manufacturing usually requires time to design, produce, inspect, and revise tooling. That investment makes sense when thousands or millions of identical parts are being produced, but it becomes harder to justify when every part needs to match one patient.
Without dedicated tooling, a patient-specific workflow becomes much more realistic. In the future, imaging data could help generate a customized design that is manufactured near the point of care.
The vision is straightforward: scan, design, print, and prepare the component for its intended procedure.
The real medical workflow is more involved. A finished device still has to meet the necessary requirements for material control, post-processing, testing, sterilization, process validation, and regulatory review. The FDA notes that 3D-printed medical devices are generally subject to the same regulatory requirements as devices made through traditional methods.
Still, removing conventional tooling could make patient-matched geometries far more practical than they have been in the past.
Small Parts, Big Possibilities
Microscopic 3D printing may feel far removed from the desktop machines most of us use, but the underlying maker mindset is exactly the same.
Start with a problem.
Create a design.
Test it.
Learn from it.
Then make the next version better.
The difference is that, at the microscopic scale, the result could be a tiny diagnostic channel, a less invasive instrument, a dissolvable mold, or a patient-specific medical component.
The parts may be small, but the possibilities are anything but.