The full name of nuclear pore membrane is "heavy ion microporous membrane." The term "nuclear" in its name actually refers to "heavy ions"—ions with a mass number larger than that of a helium nucleus, such as argon ions and krypton ions. Its creation is the result of a combination of "physical bombardment" and "chemical etching":
First, a heavy ion accelerator is used to accelerate these heavy ions to extremely high energies, bombarding insulating materials—commonly used ones include PET (polyethylene terephthalate) and PC (polycarbonate) in plastics—like a swarm of precise "microscopic projectiles." When high-speed heavy ions pass through the material, they leave an extremely fine "track" inside, known as an ion track. The initial channel is only about 1 nanometer wide, finer than one-millionth of a human hair.
Next, chemical etching is used to "expand the pores": the material is exposed to a specific etching solution, and the material along the ion tracks is slowly dissolved. The original 1-nanometer slit gradually enlarges, ultimately resulting in a nuclear pore membrane with controllable pore sizes. Simply put, it’s like first "driving piles" to leave tracks and then "refining the pores" to determine their size—a process akin to "embroidering" in the microscopic world.
Compared to traditional membranes: It’s a "top performer" that stands out on merit.
Just describing the production process might not be intuitive enough, but when compared with electron microscope images of traditional membranes, the "advantages" of nuclear pore membranes become immediately apparent:
To ensure stable performance, traditional membranes typically need to be over 300μm thick (1μm is one-thousandth of a millimeter), so thick that they can hardly form a standalone membrane and often require a support layer. In contrast, nuclear pore membranes are mostly only about 10μm thick, as thin as a transparent cicada wing, yet they can independently form a "single-layer membrane."
More importantly, there’s the difference in "pores": traditional membranes often have uneven pore sizes, with channels that may be curved, intertwined, or even risk fiber shedding. Nuclear pore membranes, however, look as if they’ve been processed by a "precision punching machine"—pore density can be precisely controlled, all channels are straight, like countless neatly arranged microscopic "pipes." Moreover, the material itself is stable, resistant to high temperatures, acids, and alkalis, with almost no risk of impurity shedding.
These traits make it a "top performer" in the membrane industry: it can precisely retain specific substances without "causing trouble" during filtration or transmission, something traditional membranes struggle to achieve simultaneously.
Production Challenges: "Precision Control" at the "Nanoscale"
The excellence of nuclear pore membranes comes with extremely high technical barriers. Its challenges lie entirely in "microscopic control," akin to "dancing on the tip of a needle."
First is "radiation flux control." When heavy ions bombard the material, each ion must leave a uniform track—not only must the pore density be consistent, but the distribution must also be even. There can’t be areas where pores are clustered together or sparsely scattered. It’s like punching 300 million holes on a 1-square-centimeter sheet of paper (equivalent to the pore density of a 0.22μm pore-size membrane) while ensuring the holes are neatly arranged. The difficulty is imaginable
Even more challenging is "etching precision." The pore sizes of nuclear pore membranes are mostly at the micron or nanometer level. For example, laboratories can achieve 10-nanometer pore sizes (1 nanometer is one-billionth of a meter), while mass-produced products mostly range between 0.22μm and 30μm, with a required pore size error within 10%. Take a 0.22μm pore, for example: a 10% error means each pore’s diameter can only fluctuate between 0.198μm and 0.242μm. Currently, most products in the industry have errors of 20%–50%, and very few can achieve a 10% error, highlighting the difficulty of control.
Furthermore, during etching, not only must errors be controlled, but "pore shape" must also be managed: pore channels must remain straight, not crooked, and adjacent pores must be prevented from being "connected" by the etching solution, forming "linked pores," which would render the entire membrane ineffective. Every step must be as precise as surgery—too little etching leaves pores underdeveloped, while too much ruins them.
From Small Pores to Big Impact: These Fields Can’t Do Without It
Precisely because of its "outstanding performance," nuclear pore membranes have become indispensable in several critical fields.
In healthcare, it serves as a "precision filter": during hemodialysis, its uniform pore size can retain toxins in the blood while allowing beneficial small molecules to pass through. During vaccine purification, it efficiently retains pathogens like viruses while reducing protein adsorption—excessive protein adsorption can affect vaccine efficacy, and the "low adsorption" characteristic of nuclear pore membranes effectively addresses this issue.
In the lithium battery field, it acts as an "efficient transmission channel": traditional lithium battery separators have curved pore channels, causing lithium ions to "detour" during transmission, affecting charging and discharging efficiency. The straight-pore structure of nuclear pore membranes allows lithium ions to "travel in a straight line," significantly improving transmission efficiency. At the same time, its stability reduces the risk of battery short circuits, helping high-energy-density batteries "perform more safely."
In chip manufacturing, it is a "cleanliness guardian": chip production has extremely high requirements for "cleanliness." For example, filtration during photoresist development and ultrapure water filtration require membranes that can retain tiny impurities. The precise pore size of nuclear pore membranes can block impurities, ensuring the precision of semiconductor production.
It even has unique value in anti-counterfeiting: the microporous array of nuclear pore membranes is a "hard-to-replicate password." When combined with fluorescent markers through special processes, it can be made into anti-counterfeiting labels for use on luxury goods, documents, and currency. These micropores are invisible to the naked eye but can be identified with specific devices. It’s nearly impossible for counterfeiters to accurately replicate such dense and uniform micropores, giving it inherent "high anti-counterfeiting properties."
The story of nuclear pore membranes is a microcosm of "small materials" driving "big industries." Behind it lies interdisciplinary collaboration among nuclear technology, materials science, and engineering—using heavy ion physics to "lay the foundation," relying on materials chemistry to "refine the details," and leveraging engineering technology to "promote mass production." Today, it is steadily moving from the laboratory to industrialization. Perhaps in the near future, when we use safer lithium batteries and more efficient medical devices, this thin film with "tiny pores" will be playing a role behind the scenes. This "microscopic hero" harboring great technology holds even more potential for the future.
Linde Membrane Technology has already achieved significant success in some fields. However, in the long term, we are not just a membrane material producer. We aspire to apply advanced original technologies to more areas, turning them into products and commodities that benefit more users.
