Three-Dimensional Printing in Ion Mobility and Mass Spectrometry

Interest in three-dimensional (3D) printing technology is expanding rapidly. What impact can it have in mass spectrometry? Robert Winkler, of the Center for Research and Advanced Studies Irapuato, in Guanajuato, Mexico, is exploring this question. We recently spoke with Prof. Winkler about this work.

What makes 3D-printing technology valuable in ion mobility spectrometry and mass spectrometry?

Before we started using 3D printing, we spent quite a lot of time building our prototypes. On a daily basis, new exciting ideas for improving analytical instruments are published, and we would like to test some of them. For example, ambient ionization, mass spectrometry imaging, ion manipulation, and portability are very active research areas in ion mobility spectrometry and mass spectrometry. But often, the reported devices are difficult to reproduce and are commercially not available. Using 3D printing, we can quickly build, modify, test, and share prototypes. This approach also reduces our dependence on large industrial providers, speeds up innovation, and lowers costs.

In a recent article (1), you highlight many recent developments in 3D-printing, including fused deposition modeling (FDM). How can FDM help advance ion mobility spectrometry?

Fused deposition modeling (FDM) is a widespread technology, and simple FDM printers are on sale for a few hundred US dollars. Thus, this technology is affordable for higher education and research institutions “on a budget.” Although the electronics setup is not trivial, cheap ion mobility spectrometry (IMS) devices could be built and distributed as do-it-yourself kits using FDM. IMS has less analytical power than mass spectrometry, but it is very sensitive for detecting known compounds. Thus, IMS is commonly used for chemical screening in airports.

Having IMS devices that are easy to build with FDM could support the further development of the technology and its applications, such as environmental monitoring. In the review, we presented different IMS devices and components that were built using FDM. The production of ten unibody drift tubes with a high global accuracy showed the feasibility of 3D-printed IMS analyzers (2).

Three-dimensional printing has been shown to allow for the fast and cost-effective production of microreactors for bioassays. What effect has this development had?

The development of bioassays can be tedious because multiple conditions must be tested. Producing cartridges or microreactor systems with conventional methods is only feasible for extensive studies or routine use. With 3D-printing, small series of microreactors can be manufactured and enable reproducible experiments. Later, the design of the 3D-printed gadgets can be adopted for mass production.

In your article, you discuss how 3D printing enables the "peer production" of scientific devices. Can you expand on what "peer production" means and how that connects to the results 3D-printing has achieved so far in ion mobility and mass spectrometry?

“Peer production” is the community-driven development and manufacture of goods. Its participants have diverse motivations—not only monetary—for sharing their knowledge. The concept of peer production applies mainly to non-rival goods such as information (3). Wikipedia and Linux are examples of successful peer production, with thousands of volunteer contributors.

We develop analytical devices with public funding and are employed in public institutions. Thus, we should make our results accessible to the people and companies that support our work. If another research group or company adopts our designs, my salary is not affected (“non-rival”), and maybe the users cite us, which helps us justify new project funding. If the situation is the other way around, we also profit from using published files of 3D-printable devices and related literature.

Several groups share their 3D-printing files for IMS and MS parts, either as supplemental material to their papers or on personal request. For example, the files for building or modifying our 3D low-temperature plasma (LTP) probe are freely available online (4). Anyway, providing the necessary files for reproducing 3D-printed prototypes is good practice for publications in analytical chemistry and should be further encouraged by the journals.

What are the major challenges that remain with developing 3D-printing technology for use in mass spectrometry? Have some of these challenges been resolved?

Additive manufacturing has various limitations. Some shapes and geometries, for example, overhangs, are difficult to print. Also, the surface quality and spatial resolution of parts may be insufficient for specific applications. Also, not all materials are available for 3D printing. However, there's already a wide variety of polymer filaments with diverse properties, such as flexible or conductive.

Three-dimensional printing is a powerful production method, but we have to design printable parts. In some cases, a professional service can print the final component. But often, the combination of 3D printing with conventional manufacturing methods, and using off-the-shelf parts where possible, leads [subject of the verb is combination] more quickly to the desired product.

There are also innovative solutions to overcome particular problems, such as the metal coating of 3D-printed parts for making them conductive (5).

What are your next steps in researching 3D-printing technology, and in what direction do you see the application of 3D-printing heading in the future?

Combining different methods with a low analytical resolution often gives more information for identifying and quantifying compounds than using a single high-resolution method. Thus, we develop functional modules that fit together, resulting in analytical systems for given applications. For example, our 3D-printed ion source and our Open LabBot (built with 3D-printer technology) enable mass spectrometry imaging and high-throughput analyses (6). Now, we are working on a modular miniature mass spectrometer for the real-time analysis of volatile organic compounds (VOCs) and a platform for metabolic phenotyping. Three-dimensional printing plays a central role in the development of our prototypes. Besides, we are creating software to process such multi-dimensional data.

The possibility of drawing objects in free software and producing them with good quality at low cost motivates students and scientists to bring their ideas to practice. In this way, analytical chemists are not only consumers anymore but also empowered to create their own devices and share them with the community.

References

(1) H. Guillen-Alonso, I. Rosas-Roman, and R. Winkler, Anal. Methods 13, 852–861 (2021).

(2) B.C. Hauck, B.R. Ruprecht, P.C. Riley, and L.D. Strauch, Sens. Act. B. 323, 128671 (2020).

(3) Y. Benkler, The Wealth of Networks: How Social Production Transforms Markets and Freedom (New Haven and London, Yale University Press, 2006).

(4) S. Martinez-Jarquin, A. Moreno-Pedraza, H. Guillen-Alonso, and R. Winkler, Anal. Chem. 88(14), 6976–6980 (2016).

(5) S.D.S. Gordon and A. Osterwalder, Phy. Rev. Appl. 7(4), 044022 (2017).

(6) I. Rosas-Roman, C. Ovando-Vazquez, A. Moreno-Pedraza, H. Guillen-Alonso, and R. Winkler, Microchem J. 152, 104343 (2020).

Robert Winkler is the PI of the Laboratory for Biochemical and Instrumental Analysis in the Department of Biochemistry and Biotechnology at the Center for Research and Advanced Studies (CINVESTAV) Irapuato, in Guanajuato, Mexico. Direct correspondence to: robert.winkler@cinvestav.mx.

Will Wetzel is an assistant editor for LCGC North America. Direct correspondence to: wwetzel@mjhlifesciences.com.