This Is Heavy

Unless you have spent some time working in the sciences, you may never have heard of a mass spectrometer. But whether or not you are familiar with this instrument, it is vitally important to a number of applications. A mass spectrometer is a sophisticated analytical tool used to measure the mass-to-charge ratio of ions, providing invaluable insights into the composition of a sample. This versatile device finds extensive use in various scientific disciplines, including chemistry, biology, and physics. From identifying unknown compounds in environmental samples to elucidating the structure of complex biomolecules, mass spectrometers play a pivotal role in advancing our understanding of the natural world. Additionally, they are indispensable in fields such as forensic science, pharmaceuticals, and environmental monitoring, where precise analysis of substances is crucial for ensuring accuracy and reliability in research.

Unfortunately, these machines can be extremely expensive. Moreover, they are complex, bulky, and easily damaged. These factors generally limit their use to controlled laboratory settings at well-funded institutions. But identifying unknown samples has important applications everywhere, from remote locations on Earth to the far reaches of our solar system. Accordingly, more durable, and less costly, mass spectrometers would be highly desirable.

The first step toward that future reality has recently been taken by a team of researchers at MIT and Ardara Technologies. They have shown that it is possible to 3D print the miniature filters, called quadrupoles, that are a key component of any mass spectrometer. Using their methods, a quadrupole can be produced in a few hours for a nominal cost. Under normal circumstances, the same filter would take weeks to produce and might cost upwards of $100,000. These 3D-printed filters are also very light in weight, adding to the portability of instruments that incorporate them.

The quadrupoles are produced using a cutting edge additive manufacturing technique called vat photopolymerization. In this process, a piston pushes a liquid glass-ceramic resin near a grid of LEDs, creating a very thin layer of material between the piston and LEDs. The LEDs then illuminate to cure the resin and create a layer of the design. The process then repeats to build up the 3D object one layer at a time. It is a very precise process, and using a glass-ceramic resin, the final product can withstand temperatures of up to 900 degrees Celsius without degrading.

Vat photopolymerization has the added advantage of being able to print virtually any shape, like the hyperbolic rods and networks of triangular lattices that would be very difficult, or impossible, to produce with traditional additive manufacturing techniques. Finally, electroless plating was utilized to coat the prints with a thin metal film so that they would be electrically conductive, which is essential for their proper functioning as quadrupoles.

A printed filter was inserted into a commercial mass spectrometer to test its performance. At about one-quarter the density of the existing commercial filter, the new design was much lighter. However, the researchers found that they could achieve even higher resolutions using their quadrupole than was possible with commercial filters.

Looking ahead, the team is planning to work toward developing longer filters. Longer filters boost the performance of the device, and enable it to make more precise measurements. They also intend to explore additional materials that could be leveraged in producing the filters, with the hope that they might achieve better heat transfer.

A member of the research group noted that their “... vision is to make a mass spectrometer where all the key components can be 3D printed, contributing to a device with much less weight and cost without sacrificing performance. There is still a lot of work to do, but this is a great start.”