'The best of SLA can't do this' - BMF's John Kawola discusses applications of PµSL 3D printing

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“The best of SLA can’t do this.”

CEO John Kawola is gesturing to the dozens of 3D printed components on Boston Micro Fabrication’s (BMF) RAPID + TCT booth.

These parts, which range from electrical componentry to medical devices to microfluidic devices, have been additively manufactured on BMF’s microArch series of 3D printers, of which there are seven models. The parts are small – very small – and the printers are conspicuous in their absence.

Though BMF is at a trade show – where the intention is to sell products – alongside hundreds of other machine providers, it has decided to forego the opportunity to show off the microArch S230, for example, that it launched at the last RAPID + TCT event.

“I don’t think they need to see the machine,” Kawola suggests, “they need to see the parts.”

This idea stems from the situation the company was put in during the COVID-19 pandemic. BMF launched in the US in the weeks preceding COVID lockdowns and in a bid to build up some business, commenced the additive manufacture of samples for its customers, which were sent out via mail to secure orders. It worked, and today the company has more than a couple of hundred users of its Projection Micro Stereolithography (PµSL) technology.  

The application of one of those customers rests between Kawola’s finger and thumb. IMcoMET is using PµSL to develop a technology based on microfluidics and microneedles which allows the microenvironment of cancerous tumours to be physically removed. This device uses two tiny stainless-steel needles with one injecting a carrier fluid and the other extracting it. Primarily designed for skin cancer patients, the fluid travels between the two needles within the skin, mixes with the cancerous cell fluids and drains all the signals that create the cancer cells in that area. 

This device, the microneedle-Duo (M-Duo), leans on PµSL technology for the caps and the lid that holds the needles in place. The parts contain two channels of 100µm diameter, positioned in parallel at only 20-40µm distance from each other. 

“It’s a good example of a part that they want it to function, they want to hold these needles, they need to have channels on the inside and it would be very difficult to mould to get all the functionality they want,” Kawola says. 

The parts that BMF is enabling are ‘emerging applications’, per Kawola – those that haven’t been possible before because they were too difficult to mould, machine or even 3D print. This comes at a time, so far as BMF can see, when product designs – from direct delivery devices to antennas – are reducing in size.

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“As things get smaller and smaller, they get harder and harder to mould, or harder and harder to machine,” Kawola says. “It tilts that balance of, ‘well, maybe we should 3D print?’ Everybody in this building is like, ‘should I 3D print or should I mould?’ They do the math, and they figure it out. What happens with really small parts is that the math [changes] and that’s the biggest trend that we see with our customers and why they’re attracted to this.”

As such, BMF has been able to make headway in several industries, printing the componentry that holds lenses and chips in electronics, for example, or additively manufacturing the distal tip of a single-use endoscope.

This latter application has been developed by RNDR Medical. The endoscope is utilised for direct visualisation and navigation to diagnose and treat disorders in the urinary tracts, such as kidney stones or urothelial carcinoma. The distal tip is a key component of the device, housing the camera chip and illumination source, while also directing fluid paths for irrigation and providing the link from the working channel (where therapeutic tools are passed through) to the exterior anatomical environment. These elements require a high degree of precision, while there can be no fluid ingress into the device. It has a .130-inch diameter profile, an exterior geometry that must be atraumatic to the anatomy and a wall thickness that, prior to BMF, was only achievable through niche micro moulding. Component volumes can be in the tens of thousands per year.

With PµSL, RNDR has been able to achieve resolutions of between 2µm-25µm and tolerances of +/- 10µm-25µm, while also experiencing a streamlined iterative development cycle (days versus weeks and months). Around 500 units can be produced within a single build cycle and Kawola says it makes for a good end-use case because each distal tip is used for a matter of minutes, as opposed to years. 

“They stick it in your body for 15 minutes – hopefully only for 15 minutes – and when they pull it out, they take the end off and throw it away,” he explains. “So, it has to be biocompatible, it has to be strong enough to what it needs to do for 15 minutes, but it doesn’t have to last for ten years.”

The company perceives a big play in the medical sector and has been quick to align with 4D Biomaterials, a young company developing a range of polymeric 3D printing resin inks that can enable additively manufactured implantable medical devices which degrade and resorb into the body over time. Through its partnership with BMF, the plan is to tune 4D Biomaterials’ 4Degra bioresorbable resin inks to its microArch printer series to facilitate the printing of micro-scale geometries in orthopaedic devices and soft tissue applications. 

It is an extension of BMF’s play in the medical field, where it has recognised that, although there is always a regulatory hurdle to overcome, the technical challenge is often not nearly as daunting. 

“In medical devices, some of these technical barriers we’re finding to be maybe not as challenging. Now, we haven’t got over those barriers for most applications yet, but we look at that target and we’re like, ‘yeah, we could probably do that.’ Now, there’s a regulatory hurdle that’s always going to be there, but we saw what [4D Biomaterials] had developed and we’re socialising that material with a number of our customers.”

So far, BMF has a materials portfolio that includes GR, which has good stiffness, impact strength and heat resistance; HT 200, which can withstand temperatures up to 200°C; and BIO, which is a biocompatible resin suitable for non-implantable medical applications. There is also the RG material from the BASF Forward AM Ultracur3D photopolymer resin line, which is suitable for electrical cases, medical devices, and functional prototyping.

The RG material is a good example of BMF’s strategy when it comes to materials. Recognising the big chemical companies are unlikely to customise materials for a small firm in a niche section of the market, BMF has ‘tried to be a little bit opportunistic, looking what’s out there in the world and [if we like it], let’s see if we can get that to use on our machine.’

“Our strategy is can we take a material that they’ve already developed for some of the other DLP platforms, and we can we tune it to get it to work on our machine?” Kawola says. “And it doesn’t always work, but I’d say 75% of the time we can get it to work. What’s the difference between our machine and, let’s say, a [3D Systems] Figure Four machine? We’re printing at much finer layers. That’s the primary difference and so we need to tune the material by adding absorbers or inhibitors and then get it to work.”

Once those materials have been tuned to the PµSL process, BMF believes users of microArch printers can pursue the prototyping and production opportunities that have previously frustrated them. The company is confident that, it is not just offering a capability that wasn’t there but is also doing so in an economically attractive way. Kawola points out that not only is 3D printing micro-scale parts removing the large costs of micro moulding, but because such little material is used to print each part, the material costs that are typically factored into cost comparisons between printing and moulding are significantly lower. 

With the assurance that its technology has the potential to open those doors for its 200 customers, BMF is confident its small printing capabilities will have a large impact. The company has recently raised 43 million USD, which it plans to harness to advance product development, sales, marketing, and customer support, while new facilities have been opened in Greater Boston and Shenzhen. Now, Kawola believes the task at hand is to continue building momentum. 

“We’re now at a phase where customers are buying the second one and the third one, the fourth one, which has been very positive,” Kawola finishes. “It’s continuing to work on the materials to get over those humps in terms of end-use applications, something we’re always working on. And we have a couple of new platforms coming in the future to address – when we look at resolution, accuracy and detail, we think we’re pretty good here, I’m not sure we need to be better than this – so most of the thing, when we think about development, is how we maintain all this goodness, in terms of accuracy and resolution and surface finish? And how do we go faster? How do we make it easier to use for the customer? How do we make it more consistent? I think those are the things when we think about the product roadmap we’re talking about.”