A class of materials that consist almost entirely of air, yet rival or exceed the mechanical performance of steel by weight, has moved from laboratory curiosity to active engineering research over the past several years. Silica aerogel, sometimes called “frozen smoke,” is 99.8% air by volume, and newer variants built from graphene and metal microlattices push the boundaries of what empty space can do. The gap between these lab results and commercial products is narrowing, but significant questions about cost, durability, and scalability remain unanswered.
Frozen Smoke: Where It Started
Silica aerogel earned its nickname because it looks like a translucent wisp of solidified vapor. Its internal structure is a tangled network of nanoscale glass filaments that trap pockets of gas, producing a material that is 99.8% air by volume. That extreme porosity is not a weakness. It is the source of the material’s remarkable thermal insulation: heat struggles to conduct through a solid that barely exists. Engineers at NASA missions recognized this property early and used silica aerogel as the capture medium aboard the Stardust spacecraft, where it gently decelerated and trapped comet particles traveling at hypervelocity speeds without destroying them.
The Stardust application demonstrated that aerogel could absorb enormous kinetic energy relative to its mass. But silica aerogel is brittle. Drop a piece and it shatters. That fragility limited its usefulness to niche roles like insulation tiles and particle collectors. Researchers spent the following decade trying to answer a pointed question: could the same air-dominated architecture be rebuilt with tougher base materials so the resulting solid would flex instead of crack? The answer would require moving from random, sponge-like networks toward precisely engineered structures whose mechanical behavior is dictated more by geometry than by the intrinsic strength of the solid skeleton.
Metal Lattices Lighter Than a Dandelion Seed
A team led by researchers at HRL Laboratories, the University of California Irvine, and Caltech answered that question with a radically different geometry. Instead of a random tangle of filaments, they designed a periodic lattice of hollow nickel-phosphorus tubes, each thinner than a human hair, arranged in a repeating three-dimensional pattern. The resulting ultralight lattice, published in Science, achieved densities as low as 0.9 mg per cubic centimeter. That is roughly 100 times lighter than Styrofoam. A sample large enough to rest on top of a dandelion puff would not crush the seeds, a visual that helped communicate just how extreme these densities are.
What separates these lattices from earlier aerogels is their architecture-driven mechanical response. When compressed by 50%, the microlattice springs back to nearly its original shape. That recovery is not a property of the nickel itself but of the hollow-tube geometry, which allows walls to buckle and unbuckle elastically. The measured Young’s modulus and energy absorption per unit mass outperform many conventional foams and honeycombs, indicating that the stiffness and strength scale in a predictable way with density. The AAAS press materials accompanying the Science paper highlighted these results, but the authors also noted that nickel-phosphorus is expensive to electroplate at scale and that thin-walled tubes are vulnerable to fatigue under repeated loading. Those caveats underscore a central challenge: the same ultrathin features that make the lattice so light also make it sensitive to manufacturing defects and long-term wear.
Graphene Aerogels Push Strength Further
Graphene offered a way to keep the air content high while dramatically improving resilience. A study in Advanced Materials reported graphene aerogels with densities as low as 3 mg per cubic centimeter and recoverable compressibility greater than 90%, meaning they could be repeatedly squashed and still spring back. In these materials, two-dimensional graphene sheets assemble into a three-dimensional scaffold, distributing stress across a continuous carbon network rather than through isolated struts. The result is a foam-like solid that is mostly empty space yet can endure large deformations without permanent damage, a combination that traditional polymer foams struggle to match at comparable weight.
Separately, research in Nature Communications described graphene aerogel microlattices fabricated through 3D printing using direct ink writing, a technique that allows precise control over internal architecture. Those microlattices exhibited supercompressibility up to 90% compressive strain, according to the authors, and largely recovered their shape after unloading. The two lines of work align in showing that graphene-based aerogels can be both ultralight and mechanically robust, though the exact recovery thresholds differ slightly depending on fabrication method and testing protocol. Popular coverage often compresses these nuances into a single “stronger than steel” sound bite, but the underlying studies emphasize how processing choices (ink composition, printing path, drying conditions) tune properties such as stiffness, energy absorption, and fatigue life.
From Oil Spills to Heavy Metals: Early Use Cases
A separate line of work at Zhejiang University produced carbon-based aerogels with a reported density of approximately 0.16 mg per cubic centimeter, lighter even than the metallic microlattices, and an ability to absorb up to 900 times their own weight in oil. That absorption figure points to environmental cleanup as a near-term application. In principle, a lightweight sponge that soaks up oil but not water can be deployed across large spill areas, then squeezed or burned to recover or destroy the captured hydrocarbons. Because the aerogel itself is so light, most of the mass to be transported is the contaminant, not the sorbent, potentially reducing logistics costs in remote or offshore operations.
Meanwhile, researchers have demonstrated that soaking graphene aerogels in ammonia can mechanically strengthen them while tuning density and volume, and those ammonia-treated variants showed quantified adsorption performance toward lead ions (Pb²⁺), according to a study in Scientific Reports. Heavy-metal filtration in contaminated water is a practical problem that does not require aerospace-grade production volumes, making it a plausible early commercial use case. In such systems, the aerogel’s enormous internal surface area provides abundant binding sites for dissolved ions, while the open pores allow water to flow with relatively low pressure drop. Once saturated, the material can be regenerated or disposed of in a controlled way, concentrating the pollutants into a smaller, more manageable volume.
Why the Steel Comparison Needs Context
Headlines, including the one above this article, often claim these materials are “tougher than steel.” That framing requires careful reading. No peer-reviewed study in the available literature directly compares an aerogel microlattice to a steel coupon under identical ASTM loading conditions. What the research does show is that on a strength-to-weight or stiffness-to-weight basis, these air-dominated structures outperform steel and most engineering alloys by large margins. A cubic centimeter of steel weighs roughly 7,800 mg. A cubic centimeter of metallic microlattice weighs 0.9 mg. Even if the microlattice absorbs only a tiny fraction of the absolute force that steel can handle, it does so with a mass penalty that is essentially zero. For applications where weight drives cost, such as aerospace, satellites, or high-speed transportation, this trade-off can be transformative even if the absolute strength is modest.
Context also matters when translating laboratory demonstrations into real-world components. The most impressive numbers typically come from small, carefully fabricated samples tested under ideal, uniaxial loading. Structural parts in service see multiaxial stresses, impacts, temperature swings, and manufacturing imperfections. Joining ultralight lattices to conventional materials without creating weak interfaces is another unsolved problem. Cost remains a major barrier as well: the photolithography, templating, and 3D-printing routes used to create ordered microlattices are slow and capital-intensive, and the precursors for high-quality graphene are still expensive. The path from “lighter than a dandelion seed” to “bolted into an airplane wing” will likely run through niche roles (thermal insulation, vibration damping, filtration, and specialty packaging) where the unique combination of low weight and tailored mechanical response justifies the added complexity. In that sense, the promise of air-like solids is less about replacing steel outright and more about opening design spaces that dense materials could never reach.
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*This article was researched with the help of AI, with human editors creating the final content.
