A complete 3D-printed tool kit for Solid-State NMR sample and rotor handling

Abstract

Solid state NMR (SSNMR) is a highly versatile and broadly applicable method for studying the structure and dynamics of biomolecules and materials. For scientists entering the field of SSNMR, the many quotidian activities required in the workflow to prepare samples for data collection can present a significant barrier to adoption. These steps include transfer of samples into rotors, marking the reflective surfaces for high sensitivity tachometer signal detection, inserting rotors into the magic-angle spinning (MAS) stator, achieving stable spinning, and removing and storing rotors to ensure reproducibility of data collection conditions. Even experienced spectroscopists experience occasional problems with these operations, and the cumulative probability of a delay to successful data collection is high enough to cause frequent disruptions to instrument schedules, particularly in the context of large facilities serving a diverse community of users. These problems are all amplified when utilizing rotors smaller than about 4 mm in diameter. Therefore, to improve the reliability and robustness of SSNMR sample preparation workflows, here we describe a set of tools for rotor packing, unpacking, tachometer marking, extraction and storage. Stereolithography 3D printing was employed as a cost-effective and convenient method for prototyping and manufacturing a full range of designs suitable for several types of probes and rotor geometries.

Keywords: 3D Printing; Rotor packing; Sample preparation; Tachometer marking.

Figure 1.

CAD drawings and printed parts of the modified rotor packing devices. (a) Drawing and printed parts of the “nozzle” design from Hisao et al. (Ref [13]). (b) Drawing and printed parts of the “notch” design suitable for smaller rotor sizes. (c) Rotor unpacking adapter. (d) Sample transference adapter. (e) Drawings of various rotor packing devices for pencil-style and Bruker style rotors.

Figure 2.

Traditional and modified rotor extractions tools. (a) Traditional bulb-tube rotor extraction tool. (b) Modified rotor extraction tool with a bent tip and soft tubing. (c) Close up picture of the bend tip extractor tool with a rotor, Eppendorf tube and a rotor holder. (d) Bent-tip extraction tool with guides that clamps onto probe bodies. (e) Rotor stored vertically in Eppendorf tube, which is held vertically inside a Falcon tube by another adapter.

Figure 3.

Tachometer marking guide for 1.6 mm and 3.2 mm pencil style rotors. (a,b) two views of the 3D CAD drawing of the guide (c) a 1.6 mm and a 3.2 mm rotor top cap marked using the guide (d) tachometer readout of the 3.2 mm rotor spinning at 10 kHz.

Figure 4.

Example of CAD model optimized for SLA printing and the corresponding printed parts in Clear V4 and Durable V2 resin. (a) Drawing of part C in Figure 1a with flat bottom surfaces and standard threads cross sections. (b) modified design with concaved bottom surfaces and reduced threads cross sections. (c) Part printed with Clear V4 resin right after printing and with the supports removed. (d) Part printed with Durable V2 resin right after printing and with the supports removed.