Accurate and on-demand chemical sensors: A print-in-place ion mobility spectrometer

Additive manufacturing is increasingly being used for novel applications including the fabrication of components for analytical instrumentation and chemical sensors. Fused deposition modeling (FDM) has been used to fabricate drift tubes for ion mobility spectrometry (IMS), which ionize, separate, and identify analytes of interest within a sample mixture. IMS drift tubes consist of both conductive and nonconductive materials, as well as complex features such as suspended wires spanning their inner diameter. The accuracies of these drift tubes are partially dependent on the accuracy of their fabricated length. As such, the ability to fabricate them in a print-in-place manner, instead of as an assembly of separately printed subcomponents, would reduce the uncertainty in this critical variable. However, 3D-printed drift tubes have previously only been produced by dual extrusion FDM and were therefore unable to print the suspended wires above the printer bed. This has forced the continued use of modular designs and assemblies that may introduce and compound error in the drift tube length. Here, the first print-in-place and non-modular ion mobility spectrometer is demonstrated and used to evaluate the accuracy of FDM as a manufacturing method. It is ultimately shown that the fabrication process accurately preserves the designed drift tube length.