Nano/micro 3-D printing is capable of generating complex, minute components
by MIT Technology Review Insights January 11, 2018
Traditional manufacturing faces significant challenges when tasked with quickly creating small components that involve highly complex, minute, precision-crafted structures—items such as miniature connectors and micro-lenses for endoscopes. All these parts require high-end precision manufacturing to create an exact surface profile and complicated internal structures, which is costly. Now, cutting-edge nano/micro 3-D printing technology is overcoming these hurdles by providing simpler customization and faster production of these complicated parts, while also answering the growing demand for precision manufacturing in other fields.
Market researcher Technavio predicts that the global 3-D printing services market will continue to grow by 44 percent annually into 2021. The expanding need for precision manufacturing is also fueling the growth of precision 3-D printing services. The global eyewear market, for example, is expected to have a 3.7 percent compound annual growth rate (CAGR) through 2018, reaching $130 billion, according to Transparency Market Research.
“[Many] manufacturing problems can now be solved with this new fast and cheap production capability, so the potential market for nano/micro printed parts is just coming into view,” says William Plummer, senior scientist and advisory board member for BMF Material Technology, a Boston/Shenzhen-based startup firm that manufactures nano/micro 3-D printers and materials, as well as custom products for other companies using its equipment.
While well-known 3-D printing startups such as Desktop Metal and Carbon have already attracted a lot of attention in the market, they focus on larger-scale manufacturing. As the technology has advanced, it has become more adept at creating more detailed and smaller components.
Nano/micro 3-D printing is capable of generating complex, minute components. This is the most precise incarnation of 3-D printing technology, and it is poised to revolutionize the precision component manufacturing industry. Now, companies such as BMF are bringing this technology to a new level with printers that have micrometer/nanometer resolution and the capacity to perform high-volume manufacturing. What sets BMF apart, says Plummer, is the equipment’s level of rigor and the unique choices of materials and processes: “BMF’s precision 3-D printing technology can make small mechanical parts, such as tiny springs, special electrical connector shapes, and even complicated and demanding devices such as cardiac stents.”
How It Works
Few technological advances have captured the public’s imagination and inspired engineering and artistic creativity to the same extent as 3-D printing, especially nano/micro 3-D printing. From a digital file, it’s possible to create a physical three-dimensional object. While not a new technology, recent advancements have made it a more practical way to create prototypes, one-off components, and items too expensive or difficult to manufacture using traditional methods such as molding and CNC (computer numerical control) machining.
BMF uses a technique called Pulse (Projection Micro Litho Stereo Exposure), which is similar to the method utilized in a microscale video display device when a series of images are sequentially projected through a reduction lens to cure light-sensitive photopolymer resin. When the reduced image pattern is focused on the photosensitive resin, the ultraviolet light initiates the curing or hardening process—which is known as photocrosslinking. Only the area illuminated by the light cures and hardens into the prescribed 3-D form. The projected light patterns are defined by the 3-D images, which are the sections of a computer-generated 3-D model. Combined with various post-processing techniques, BMF can manufacture a wide range of products, including such items as ceramics and optical lenses.
The primary difference between nano/micro and “traditional” 3-D printing is the degree of precision and resolution enabled by nano/micro 3-D printing. When describing this method of 3-D printing, resolution enters the meso, micro, and nano (i.e., one billionth of a meter) levels. This caliber of 3-D printing can replicate miniature, truly microscopic components at levels of detail and precision that are impossible to achieve with typical 3-D printing.
In recent years, 3-D printing has reached the point where consumers can purchase a 3-D printer for anywhere from $200 to $500. However, these low-end printers bear little resemblance to the sophisticated nano/micro 3-D printers that companies such as BMF now build and use for manufacturing various components.
BMF entered the high-resolution nano/micro 3-D printing market in May 2016, when it spun off from the Nanophotonics and 3D Nanomanufacturing Laboratory at MIT. The company’s technology is based on the same technology that was named one of MIT Technology Review’s 10 breakthrough technologies in 2014 and 2015. (In fact, Nicholas Fang, co-founder/chief scientist at BMF, is part of a leading nano/micro 3-D printing technology team that was recognized by MIT Technology Review in 2015.)
BMF focuses on manufacturing smaller precision components, yet at the higher volumes required by industry segments such as medical devices. “BMF’s 3-D printing system can reach a high volume due to the small size of the components we manufacture,” says Xiaoning He, co-founder/CEO of the company. Small part sizes allow for large numbers of components to be printed simultaneously. For example, BMF’s 3-D printers can manufacture hundreds of lenses with a diameter of about one millimeter within an hour, resulting in a manufacturing capacity of hundreds of thousands of pieces a year—which can meet volume demand from endoscope manufacturers. In addition, every single part in a batch of components can be custom made regardless of the number of components being manufactured. These capabilities can meet the volume demands of industrial customers that need small precision components.
With its innovative approach, the BMF team has targeted the optical industry. The lucrative optical eyeglass market in China alone represents $12 billion annually. Most eyeglasses are not truly personalized to an individual’s needs and specifications but are based on standard prescriptions. “Complicated eyeglasses, such as free-form lenses, are expensive,” says Yi Zhen, deputy director of the Medical Technology Transfer Department at Beijing Institute of Ophthalmology, Beijing Tongren Hospital. “For example, the retail price for a pair of personalized free-form lenses [using traditional manufacturing] can reach as high as $1,300.”
“The human eye is a complex organ, and it is not a perfect optical system. No two eyes are the same,” says Zhen. “However, traditional lenses are produced from semi-finished lens blanks that are factory-molded in mass quantity. Personalized free-form lenses hold the potential to free eyeglass wearers from the optical compromises of traditional, mass-produced lenses. Traditional personalized free-form lenses require expensive machinery … so that most people cannot afford it. Thus, most patients can’t achieve ideal vision correction and their eyesight keeps deteriorating.”
Beijing Tongren Hospital is the largest ophthalmic hospital in China, with about one million patient visits a year. Ningli Wang, a professor at Beijing Tongren, and his team, have joined up with BMF to produce low-cost personalized free-form lenses according to each individual’s prescription. The team has successfully designed and manufactured a sophisticated personalized lens with the following design features:
Toric design that corrects astigmatism and reduces aberrations;
Aspherical design that corrects myopia and reduces the lens edge thickness;
Peripheral defocus design that controls the development of myopia in children.
While such a free-form lens is difficult and expensive to produce traditionally, with BMF’s technology, it takes only about four hours to be manufactured, and the lens has a cost similar to that of a regular lens. “With much lower system costs and speed of production, 3-D printed lenses are set to revolutionize the supply of special spectacle lenses to the ophthalmic profession,” says Mo Jalie, senior scientist and advisory board member for BMF.
BMF’s technology can also potentially revolutionize many other ophthalmic areas, including the creation of custom-made corrective contact lenses that aid patients with complex aberrations after such issues as a corneal transplant, keratoconus (a progressive eye disease in which the normally round cornea distorts into a cone-like shape), and conditions caused by external injuries. “3-D printing for the optical lens industry is like digital printing for the publishing industry,” says Wang. “This new technology results in faster, less expensive, more flexible, and accurate lens production.
New Manufacturing Dimensions
There are myriad other precision use cases for nano/micro 3-D printing, such as cardiac stents, endoscope lenses, and specific electrical connectors, says Xiaoning. Currently, laser machining is required to carve out the complex internal structure of cardiac stents. 3-D printing can more easily generate the necessary structure, enable more sophisticated designs, and dramatically lower costs when compared to traditional manufacturing methods.
Electrical connectors are also growing smaller and more complex. Nano/micro 3-D printing technology gives engineers the tools to design intricately complex and irregularly shaped connectors. Xiaoning says BMF has also received orders in many other areas including precision ceramic components.
As with any emerging technology, nano/micro 3-D printing is becoming more precise, more capable, and less expensive. It can deliver greater accuracy at a significantly lower cost and is faster and simpler than traditional methods yielding similar levels of precision.
“The worldwide market for highly precision manufactured parts is highly demanding and lucrative. And a lot of the time, traditional technology simply doesn’t work at all,” says Xiaoning. When describing the challenges of manufacturing microscopic components, he quotes an industry phrase, “Sometimes we say, ‘The smaller, the harder.’”
For more on nano/micro 3-D printing technology, visit www.bmftec.cn