On March 18, 2025, U.S. Patent No. 12253582 was published, disclosing a gas loader cell designed for solid-state Nuclear Magnetic Resonance (NMR) spinning or static rotors. Developed by inventors Jason Mast (Plant City, FL) and Edwin Rivera (Land O’ Lakes, FL), and assigned to the University of South Florida (Tampa, FL), this apparatus addresses challenges related to vacuum and gas exposure during solid-state Magic Angle Spinning (ssMAS) experiments. In particular, the gas loader cell promotes improved efficiency, durability, and affordability compared to traditional glass-based rotor loader cells.
Background of Conventional Solutions
Solid-state NMR spinning or static rotors typically require carefully controlled environments to evaluate samples under vacuum or exposure to specific gases. In ssMAS experiments, practitioners often need to:
- Vacuum Out Air and Moisture: Remove ambient air and moisture to ensure accurate NMR readings.
- Introduce Gases: Inject isotopically labeled gases or other specialized gasses that provide enhanced or specific signals.
- Seal the Rotor: Ensure the sample remains exposed to the gas or remains under vacuum throughout the experiment.
Historically, laboratory personnel accomplished this via custom glass cells. These glass-based solutions present several challenges:
- Fragility and Expense: Glass components can break easily, leading to additional costs and potential downtime.
- Complex Manufacturing Requirements: Each glass loader cell is built in specialized glassblowing facilities, which can be both expensive and difficult to scale.
- Large Internal Volumes: Traditional glass setups can have significant internal space, which leads to inefficient use of expensive isotopically labeled gases.
Because many institutions find it increasingly difficult to maintain specialized facilities for producing custom glass cells, there was a need for an alternative material and design that ensures reliability and portability.
Patent Summary and Core Technical Features
Patent No. 12253582 discloses a gas loader cell apparatus comprising a base and a plunger, both ideally fabricated from strong, transparent materials with acrylic-like or polycarbonate-like properties. These materials address some critical shortcomings of glass, particularly fragility and cost.
1. Miniaturized Gas Chamber
By minimizing internal volume, the disclosed apparatus uses much less isotopically labeled gas compared to conventional devices. This helps avoid wasting expensive gases, ensuring that the majority of gas goes directly into the rotor for experimentation.
2. Robust Yet Lightweight Construction
Instead of glass, the apparatus can be fabricated using 3D printing or other machining methods that work with acrylic-like or polycarbonate-like materials. This construction choice enhances:
- Portability: The loader cell is easier to move between workstations or remote sites.
- Affordability: The reliance on more readily available materials can lower production costs.
- Durability: Non-glass components are less prone to breakage.
3. Universal Rotor Accommodation
The patent describes how the loader cell can be adapted for more than one rotor size. Conventional designs often require a unique glass apparatus for each rotor dimension. The adjustable features in the new design allow for seamless loading and sealing of various rotor types, improving flexibility in multi-rotor labs.
4. Vacuum and Gas Inlet Port (Hose Barb)
The system integrates a hose barb extending laterally from the cell’s outer cylinder. This port couples directly to a vacuum line and/or gas supply line. Laboratory personnel can evacuate the inside environment to remove contaminants or moisture and then introduce a desired gas. In doing so, the apparatus:
- Establishes a reliable vacuum.
- Allows for controlled gas exposure without large volumes of wasted gas.
- Maintains an airtight seal through the use of grooves and O-rings.
5. Airtight Seal with Plunger and O-Rings
A plunger with O-rings is inserted into a “holding cylinder” on the base component. The smooth sections of the plunger and matching cylinder diameters form the necessary seal. This geometry:
- Prevents air leaks.
- Provides a secure connection without complicated assembly steps.
- Minimizes frictional issues that might otherwise impede rotor insertion or removal.
6. Molded Rotor End Cap Holder
A key innovation is the way the plunger holds the rotor’s end cap. The end of the plunger can be filled with silicone-like material to create a molded cavity. This enables:
- Accurate Placement: The rotor end cap is precisely aligned with the rotor’s open top.
- Friction-Based Retention: The silicone-like surface exerts enough friction on the end cap to hold it in place, preventing unwanted displacement under vacuum or gas pressure changes.
- Air Pocket Elimination: Small channels (gutters) can be molded to prevent air pockets behind the end cap, which can expand or contract and dislodge the cap.
Step-by-Step Usage
A typical workflow using the gas loader cell might proceed as follows:
- Prepare the Rotor: Fill a solid-state NMR rotor with the sample to be investigated. The top is left open for gas introduction.
- Position the Rotor: Place the rotor into the conical funnel inside the loader cell’s base.
- Insert and Secure the Plunger: Guide the plunger into the holding cylinder. Threads or other coupling mechanisms ensure a stable connection.
- Apply Vacuum: Attach a vacuum line to the hose barb. Pump out air to create the desired vacuum level.
- Inject Gas: Using a valve connected to the same barb, introduce isotopically labeled or other specialty gas until the pressure inside reaches the required level.
- Seal the Rotor: Advance the plunger so its silicone-lined frustoconical end presses the end cap onto the rotor’s open top. The O-rings maintain an airtight environment, sealing the gas inside the rotor.
- Remove and Transport: Disconnect the lines and move the sealed rotor to the NMR spectrometer for analysis.
This process ensures minimal waste of expensive gases. The smaller internal volume also streamlines vacuum creation, since less empty space needs to be evacuated.
Advantages and Practical Implications
- Reduced Gas Expenditure: The key advantage is minimizing the internal space that would otherwise fill with costly gas, improving research budgets and resource usage.
- Simplified Manufacturing: 3D printing or other conventional manufacturing methods can create these cells, reducing reliance on specialized glassblowing services.
- Enhanced Portability: Lower weight and higher durability support transportation of the cell without risk of fragility-related breakage.
- Broader Rotor Compatibility: The silicone-lined plunger end can be adapted to various rotor sizes and designs.
Conclusion
Patent No. 12253582 outlines a compact, durable, and efficiently designed gas loader cell for solid-state NMR spinning or static rotors. By utilizing alternative materials and a minimal internal volume, the invention addresses cost, fragility, and gas conservation issues that often burden glass-based designs. Laboratory personnel working in ssMAS experiments can benefit from an easier, more portable, and more cost-effective method of introducing gases and sealing rotors under vacuum.
The flexible plunger design, universal accommodation for multiple rotor sizes, and integration of a hose barb for vacuum or gas supply lines represent a distinct technical approach to an otherwise challenging aspect of NMR analysis. As research continues to rely on isotopically labeled materials, solutions like this gas loader cell can streamline experimental workflows and reduce long-term overhead.
