With the ability to print metal structures with complex shapes and unique mechanical properties, metal additive manufacturing (AM) could be revolutionary. However, without a better understanding of how metal AM structures behave as they are 3D printed, the technology remains too unreliable for widespread adoption in manufacturing and part quality remains a challenge.

Researchers in Lawrence Livermore National Laboratory (LLNL)’s nondestructive evaluation (NDE) group are tackling this challenge by developing first-of-their-kind approaches to look at how materials and structures evolve inside a metal AM structure during printing. These NDE techniques can become enabling technologies for metal AM, giving manufacturers the data they need to develop better simulations, processing parameters and predictive controls to ensure part quality and consistency.

“If you want people to use metal AM components out in the world, you need NDE,” said David Stobbe, group leader for NDE ultrasonics and sensors in the Materials Engineering Division (MED). “If we can prove that AM-produced parts behave as designed, it will allow them to proliferate, be used in safety-critical components in aerospace, energy and other sectors and hopefully open a new paradigm in manufacturing.”

Measuring in the middle

NDE techniques involve sending signals like X-rays, ultrasound or electrical currents through objects and observing signal changes to infer information or reconstruct an image of what’s inside. NDE is important for quality control in all manufactured parts, but for metal AM, it can also help catch printing problems before it’s too late.

Most metal AM techniques use heat to bind material together, and since metals are extremely sensitive to heat, structures can change a lot during printing. Heat diffuses from the print surface into the already-printed structure, which can affect how well the material binds, create failure-inducing defects and lead to inconsistent products.

“Evolving processes in the subsurface need to be measured and characterized if you want to have a consistent print quality,” said Saptarshi Mukherjee, a research scientist in the Lab’s Atmospheric, Earth and Energy Division (AEED). “This is very challenging because most of the current NDE technologies cannot see through heat, and even infrared cameras and antennas only detect heat at the surfaces.”

Mukherjee is part of a project to monitor internal temperature during laser powder-bed fusion (LPBF) metal AM using eddy currents, swirling loops of electrical current induced by applying magnetic fields. Eddy currents are sensitive to electrical conductivity, and since conductivity is a function of temperature, eddy current sensors provide real-time localized temperature information from inside structures.

Simulations from collaborators at Michigan State University suggested the approach was viable, and the group validated it with a simple experiment, resulting in a recent paper published in Scientific Reports.

“To our knowledge, this is the first time that eddy current sensors have been used to look at these very rapid non-equilibrium thermal processes, which are suggestive of the sort of thermal processes you would see in a metal AM process,” said MED postdoc Ethan Rosenberg.

Rosenberg is now leading the experimental testing for a follow-up study using closer to real-world conditions such as non-uniform heating and faster timescales.

Trailblazers

NDE group leader Joe Tringe launched the first Laboratory-Directed Research and Development (LDRD) project in the area in 2018 and ever since, the group has been treading new ground to keep pace with metal AM.

In their first project, the group showed that millimeter wave signatures could efficiently characterize the shape of individual droplets of liquid metal used to create structures in liquid metal jetting. They eventually collected enough data to train a machine learning algorithm to predict droplet shape.

“If we can combine that feedback with system modeling, we may be able to learn whether the print parameters are working or if they need to be changed, in real time, so that we end up with what we want when we’re done,” said Stobbe.

Follow-up projects expanded to electrical resistance tomography—which measures changes in a current’s voltage and electrical potential—X-ray computed tomography, ultrasound and neutron detection, with an emphasis on lattice structures and other complicated geometries.

The group also uses NDE to inspect processing parameters like sonication—using ultrasonic waves to create vibrations and improve homogenization—in laser-based metal AM.

In a recent study published in Communications Materials, the group and collaborators at Pennsylvania State University and Argonne National Laboratory proved they could use high-speed synchrotron X-ray imaging for these measurements. The technique is the first step toward understanding sonication’s impact on printing, which will help manufacturers optimize the process to improve part quality.

“A lot of things happen in these AM processes that affect the part, but without using NDE techniques, it’s kind of a black box,” said Rosenberg. “With ingenuity and good physical understanding, you can open that box to see what’s happening inside, and that will hopefully help you control the process.”

Enabling the future

The group plans to continue evolving, improving and generalizing a variety of NDE techniques for metal AM, since different techniques are better at measuring different types of information. They also hope to train machine learning algorithms for real-time monitoring and error correction during the print to improve success.

The information they collect along the way will be crucial to enabling widespread adoption of metal AM, and they hope that their work will also help raise awareness of the opportunities for NDE in the emerging field.

“There’s a real gold rush aspect to it,” said Stobbe. “You’re out there doing or measuring things that you know no one has ever done or measured before because this is a new technology, and that’s certainly exciting.”

Other contributors to the work include MED’s Rosa Morales, Jordan Lum, Edward Benavidez and collaborators at the University of Colorado, Boulder.

The expansion has been driven by specific legal and bureaucratic levers. Foremost was an April 2020 Justice Department rule that revoked a long-standing waiver allowing DHS to skip DNA collection from immigration detainees, effectively green-lighting mass sampling. Later that summer, the FBI signed off on rules that let police booking stations run arrestee cheek swabs through Rapid DNA machines—automated devices that can spit out CODIS-ready profiles in under two hours.

The strain of the changes became apparent in subsequent years. Former FBI director Christopher Wray warned during Senate testimony in 2023 that the flood of DNA samples from DHS threatened to overwhelm the bureau’s systems. The 2020 rule change, he said, had pushed the FBI from a historic average of a few thousand monthly submissions to 92,000 per month—over 10 times its traditional intake. The surge, he cautioned, had created a backlog of roughly 650,000 unprocessed kits, raising the risk that people detained by DHS could be released before DNA checks produced investigative leads.

Under Trump’s renewed executive order on border enforcement, signed in January 2025, DHS agencies were instructed to deploy “any available technologies” to verify family ties and identity, a directive that explicitly covers genetic testing. This month, federal officials announced that it was soliciting new bids to install Rapid DNA at local booking facilities around the country, with combined awards of up to $3 million available.

“The Department of Homeland Security has been piloting a secret DNA collection program of American citizens since 2020. Now, the training wheels have come off,” said Anthony Enriquez, vice president of advocacy at Robert F. Kennedy Human Rights. “In 2025, Congress handed DHS a $178 billion check, making it the nation’s costliest law enforcement agency, even as the president gutted its civil rights watchdogs and the Supreme Court repeatedly signed off on unconstitutional tactics.”

Oversight bodies and lawmakers have raised alarms about the program. As early as 2021, the DHS Inspector General found the department lacked central oversight of DNA collection and that years of noncompliance that can undermine public safety—echoing an earlier rebuke from the Office of Special Counsel, which called CBP’s failures an “unacceptable dereliction.”

US senator Ron Wyden more recently pressed DHS and DOJ for explanations about why children’s DNA is being captured and whether CODIS has any mechanism to reject improperly obtained samples, saying the program was never intended to collect and permanently retain the DNA of all noncitizens, warning the children are likely to be “treated by law enforcement as suspects for every investigation of every future crime, indefinitely.”

Rights advocates allege that CBP’s DNA collection program has morphed into a sweeping genetic surveillance regime, with samples from migrants and even US citizens fed into criminal databases absent transparency, legal safeguards, or limits on retention. Georgetown’s privacy center points out that once DHS creates and uploads a CODIS profile, the government retains the physical DNA sample indefinitely, with no procedure to revisit or remove profiles when the legality of the detention is in doubt.

In parallel, Georgetown and allied groups have sued DHS over its refusal to fully release records about the program, highlighting how little the public knows about how DNA is being used, stored, or shared once it enters CODIS.

Taken together, these revelations may suggest a quiet repurposing of CODIS. A system long described as a forensic breakthrough is being remade into a surveillance archive—sweeping up immigrants, travelers, and US citizens alike, with few checks on the agents deciding whose DNA ends up in the federal government’s most intimate database.

“There’s much we still don’t know about DHS’s DNA collection activities,” Georgetown’s Glaberson says. “We’ve had to sue the agencies just to get them to do their statutory duty, and even then they’ve flouted court orders. The public has a right to know what its government is up to, and we’ll keep fighting to bring this program into the light.”

Other Good MagSafe Wallets

ESR Magnetic Wallet HaloLock With Find My for $40: Like Apple’s MagSafe wallet, this one has Find My support. You can use the flap on the back as a grip and fit two cards easily. It does require recharging with a proprietary cable, which is annoying, though it didn’t lose much battery life after six months. Too bad I’ve already lost the cable.

OtterBox Symmetry Series Cactus Leather MagSafe Wallet for $45: It’s nice and simple, thin, lightweight, has a strong hold on my phone case, and offers a dedicated fabric-covered slot at the bottom to push the cards out (I was able to fit three without much trouble). This OtterBox wallet is made from cactus-based leather, which feels nearly as luxurious as real leather. Just know that cactus leather isn’t as eco-friendly as it’s made out to be—these cases are still infused with layers of plastics.

Apple FineWoven MagSafe Case for $50: Any time the wallet is separated from your iPhone, you’ll get an alert and can track it in Apple’s Find My app. It has a single slot that can fit up to three cards, but to take the cards out, you have to remove it from your iPhone and push the cards up via the slot on the back. Unfortunately, Apple’s MagSafe wallets exclusively use the company’s proprietary FineWoven material (made of recycled materials). It’s a commendable effort to reduce reliance on leather production, but several WIRED reviewers have said the material doesn’t hold up all that well after some time.

Bluebonnet Minimalist Full-Grain Leather MagSafe Wallet Card Holder for $68: Bluebonnet’s wallet is thin, even with cards inside, and also comes with an elastic grip you can put your fingers through to hold the phone more securely. The magnets are stronger than those in other wallets I’ve tested, though the bottom moves a bit when using the grip. Bluebonnet claims it can fit up to three cards, but I’ve been able to fit only two (my license and debit card). It’s a struggle to insert or remove more than that.

Avoid This Wallet

Ohsnap! Snap Grip Wallet for $100: I had high hopes for this one, mainly because of its build quality. The wallet is aluminum, can hold up to eight cards (depending on whether they’re lettered or not), has MagSafe support, and comes with a grip that doubles as a kickstand. Unfortunately, the grip is made of plastic, and it broke after a short time (it won’t fold properly back into place). The magnetic hold isn’t as strong as other MagSafe wallets, even with a MagSafe-approved case on my phone. None of that is great, especially at this high price.

Benks 600D MagSafe Wallet with Stand for $33: The Benks 600D MagSafe wallet might be made with Kelvar, but it sure doesn’t feel like it. The inside shell of the wallet is made with plastic, and after just a day of use, I spotted a crack in that plastic right next to the hinge. Worse, I tried to apply a bit of pressure to see if the hinge would still hold up, which completely warped the MagSafe ring. Even without clear durability problems, this wallet wouldn’t make the top of the list. It’s reasonably priced at $30 and comes in a handful of attractive colors, but it’s limited to just three cards, and there’s no easy way to get them out.

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