Tech
Advanced sensors peer inside the ‘black box’ of metal 3D printing
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.
More information:
Lei Peng et al, In-situ 3D temperature field modeling and characterization using eddy current for metal additive manufacturing process monitoring, Scientific Reports (2025). DOI: 10.1038/s41598-025-94553-6
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Tech
I Tested Garmin Watches for a Decade While Hiking, Biking, and Climbing. Here’s What You Should Buy
Last year, Garmin introduced a Pro version that incorporates the inReach’s satellite communications savvy. Not only does it cost at least $400 more than the Apple Watch Ultra and $200 more than the regular Fenix 8, but you also have to pay for the inReach subscription plan, which has several tiers and ranges from $8/month to $50/month depending on whether you want features like unlimited texting or sending photo messages.
What you get for this mind-boggling price is a sports watch that can do anything and everything. It has best-in-class battery life (every Fenix can last for weeks on a single charge, and up to a month with solar charging) and features like the depth sensor from Garmin’s Descent line, which means this watch works as a full-on dive computer for scuba and free diving. It has a microphone and speaker for basic voice commands (although no onboard cellular connectivity), the surprisingly useful built-in LED flashlight, and Garmin’s signature built-in topographic maps, 24/7 health monitoring, and tracking for over a hundred different activities.
I’ve taken the 51-mm version on pretty much every outdoor sport—snowboarding, trail running, mountain biking, and rock climbing. Every time I use it, its capabilities far outclass my own. I have irritated many a fellow climber by attempting to track route difficulty, duration, and falls while integrating my Body Battery metrics and so on. The danger is always that you’ll spend more time fiddling with your Garmin Fenix 8 than you do with your actual sport. I have the version with the sapphire glass face and the titanium bezel, and have smashed it into rock faces with nary a scratch. If you’re up for paying the price and want a good-looking watch that will last forever (I have friends who are still wearing their Fenix 5s and 6s, and honestly, they’re fine), this is the one to get.
Best Running Watch
The Garmin Forerunner series launched in the early 2000s and has become the quintessential runner’s watch. Like all Garmins, the Forerunner comes in a range of price points, each offering different features. Last year, Garmin released the Forerunner 570 ($550), a midrange model with no LED flashlight or onboard maps, and the Forerunner 970 ($750), which is the premium version. Before I go into detail about why the Forerunner 970 is the best option, I should also say that I have tested many previous Garmin Forerunners at various price points. If you’re not a triathlete, the older Forerunners are still worth considering, and the entry-level $200 Forerunner 165 is aimed explicitly at runners, instead of including triathletes as the more expensive models do.
Tech
Save Up to 40% With These Acer Promo Codes and Discounts
Acer is one of the top largest PC manufacturers in the world, perhaps best known for its gaming line and budget-friendly options. If you’ve already got your eye on an Acer product like a laptop or monitor, and are shopping at the company’s online storefront, you should be using one of these Acer promo codes and coupons to save some cash on your purchase.
Save 40% on Accessories When You Build an Acer Bundle
If you’re buying from Acer, you’re most likely shopping for either a desktop PC or laptop. With this discount, you can get a really solid deal on accessories if you bundle it with a mouse, laptop bag, or headset. When you go to purchase a PC, just click “Build Bundle” and you’ll see some of the eligible options, all of which are reduced by 40%. The Nitro Mechanical Keyboard, for example, goes from $50 to just $30. That 40% is a real discount, too, as that same keyboard costs $50 on Amazon when I checked.
Beyond peripheral add-ons, you can also save 10% off Acer Care Plus extended service plans or McAfee LiveSafe antivirus subscriptions. You can bundle up to five products together to save the most money. If you’re headed off to college (or have a kid in the family), a bundle like this can get you everything you need for a gaming or studying setup on the go.
Shop Rotating Weekly Deals on Monitors and Gaming Gear
Acer’s PC gaming offerings come in either the flagship Predator brand or the budget-tier Nitro. Acer offers rotating weekly deals on everything from monitors to gaming laptops, some of which are my favorites that I’ve tested in their given category. The Acer Nitro V 16, for example, was a budget gaming laptop that I recommended quite a lot last year because of its incredible price. The one I tested was the entry-level version with an Nvidia RTX 5050 inside, but Acer has the RTX 5060 model in its own storefront. It’s $100 off right now at $1,200, which comes with 16 GB of RAM and a terabyte of storage. In fact, it’s only $30 more than the RTX 5050 model, despite offering a significant jump in gaming performance. These discounts are reflected right on the product pages, so there’s no promo code, discount code, or coupon code required.
Acer has a wide selection of monitors available, too, whether that’s a massive 49-incher or a more modest 27-inch gaming workhorse. One of my favorite discounts I saw right now was the Acer Nitro XV2, a 27-inch 1440p display with a 300 Hz refresh rate. It’s 44% off at the time of writing, bringing the price down to just $250. Because these discounts are swapped out on a weekly basis, it’s worth checking back to see if the product you’re eyeing has a new discount.
Select Customers Can Get 15% Off Their Purchase
Acer also offers a number of added discounts at checkout, including 15% off for students. Students will need to verify through Student Beans or SheerID. Because a lot of the devices Acer offers are budget-friendly, they can be attractive for students, and the extra 15% off is the icing on the cake.
We tested the Acer Swift 16 AI last year and really enjoyed the high-resolution, OLED screen and impressively quiet performance. Acer has the smaller version of this same laptop available, the Swift 14 AI, which is currently $150 off. You also might check out the Acer Chromebook Plus 514, a laptop we liked quite a bit when we reviewed it in 2024.
Acer offers this same 15% discount for active duty military, veterans, and their families. It also applies to healthcare professionals, which can be verified through its healthcare discount portal.
Tech
AI Research Is Getting Harder to Separate From Geopolitics
The world’s top AI research conference, the Conference on Neural Information Processing Systems—better known as NeurIPS—became the latest organization this week to become embroiled in a growing clash between geopolitics and global scientific collaboration. The conference’s organizers announced and then quickly reversed controversial new restrictions for international participants after Chinese AI researchers threatened to boycott the event.
“This is a potential watershed moment,” says Paul Triolo, a partner at the advisory firm DGA-Albright Stonebridge who studies US-China relations. Triolo argues that attracting Chinese researchers to NeurIPS is beneficial to US interests, but some American officials have pushed for American and Chinese scientists to decouple their work—especially in AI, which has become a particularly sensitive topic in Washington.
The incident could deepen political tensions around AI research, as well as dissuade Chinese scientists from working at US universities and tech companies in the future. “At some level now it is going to be hard to keep basic AI research out of the [political] picture,” Triolo says.
In its annual handbook for paper submissions, issued in mid-March, NeurIPS organizers announced updated restrictions for participation. The rules stated that the event could not provide services including “peer review, editing, and publishing” to any organizations subject to US sanctions, and linked to a database of sanctioned entities. It included companies and organizations on the Bureau of Industry and Security’s entity list and those on another list with alleged ties to the Chinese military.
The new rules would have affected researchers at Chinese companies like Tencent and Huawei who regularly present work at NeurIPS. The database also includes entities from other countries such as Russia and Iran. The US places limits on doing business with these organizations, but there are no rules around academic publishing or conference participation.
The NeurIPS handbook has since been updated to specify that the restrictions apply only to Specially Designated Nationals and Blocked Persons, a list used primarily for terrorist groups and criminal organizations.
“In preparing the NeurIPS 2026 handbook, we included a link to a US government sanctions tool that covers a significantly broader set of restrictions than those NeurIPS is actually required to follow,” the event’s organizers said in a statement issued Friday. “This error was due to miscommunication between the NeurIPS Foundation and our legal team.”
Before they reversed course, the conference organizers initially said that the new rule was “about legal requirements that apply to the NeurIPS Foundation, which is responsible for complying with sanctions,” adding that it was seeking legal consultation on the issue.
Immediate Backlash
The new rule drew swift backlash from AI researchers around the world, particularly in China, which produces a large quantity of cutting-edge machine learning papers and is home to a growing share of the world’s top AI talent. Several academic groups there issued statements condemning the measure and, more importantly, discouraging Chinese academics from attending NeurIPS in the future. Some urged Chinese academics to contribute instead to domestic research conferences, potentially helping increase the country’s influence in relevant science and tech fields.
The China Association of Science and Technology (CAST), an influential government-affiliated organization for scientists and engineers, said Thursday that it would stop providing funding for Chinese scholars traveling to attend NeurIPS and would use the money instead to support domestic and international conferences that “respect the rights of Chinese scholars.”
CAST also said it will no longer count publications at the 2026 NeurIPS conference as academic achievements when evaluating future research funding. It’s unclear if the organization will reverse course now that NeurIPS has walked back the new rule.
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