News

“Smart skin” can identify weaknesses in bridges and airplanes using laser scanner

Published

7 years ago

November 22, 2018

Recent research results have demonstrated that two-dimensional, on-demand mapping of the accumulated strain on metal structures will soon be a reality thanks to an engineered “smart skin” that’s only a fraction of the width of a human hair. By utilizing the unique properties of single-walled carbon nanotubes, a two-layer film airbrushed onto surfaces of bridges, pipelines, and airplanes, among others, can be scanned to reveal weaknesses in near real-time. As a bonus, the technology is barely visible even on a transparent surface, making it that much more flexible as an application.

Stress-inducing events, along with regular wear and tear, can deform structures and machines, affecting their safety and operability. Mechanical strain on structural surfaces provides information on the condition of the materials such as damage location and severity. Existing conventional sensors are only able to measure strain in one point along one axis, but with the smart skin technology, strain detection in any direction or location will be possible.

How “Smart Skin” Technology is Used

In 2002, researchers discovered that single-wall carbon nanotubes fluoresce, i.e., glow brightly when stimulated by a light source. Later, the fluorescence was further found to change color when stretched. This optical property was then considered in the context of metal structures that are subject to strain, specifically to apply the property as a diagnostic tool. To obtain the fluorescent data, researchers applied the smart skin to a testing surface, irradiated the area with a small laser scanner, and captured the resulting nanotube color emissions with an infrared spectrometer. Finally, two-dimensional maps of the accumulated strain were generated with the results.

Smart skin technology could be used to monitor the structural integrity in commercial jet engines. | Credit: CC0 via Pixabay, User: blickpixel

The primary researchers, Professors Satish Nagarajaiah and Bruce Weisman of Rice University in Texas, have published two scientific papers explaining the methods used for achieving this technology and the results of its proof-of-principle application. As described in the papers, aluminum bars with holes or notches in areas of potential stress were tested with the laser technique to demonstrate the full potential of their invention. The points measured were located 1 millimeter apart, but the researchers stated that the points could be located 20 times closer for even more accurate readings. Standard strain sensors have points located several millimeters apart.

What Are Carbon Nanotubes?

Carbon nanotubes (CNTs) are carbon molecules that have been structurally modified into cylinders, or rather, rolled up sheets of carbon atoms. There has been some evidence suggesting that CNTs can be formed via natural processes such as volcanic events. However, to really capitalize on their unique characteristics, production in a laboratory environment is much more efficient.

Several methods can be used for production, but the most widely used method for synthesizing CNTs is chemical vapor deposition (CVD). This process combines a catalyzing metal with a carbon-containing gas which are heated to approximately 1400 degrees Fahrenheit, triggering the carbon molecules to assemble and grow into nanotubes. The resulting formation resembles a forest or lawn grass, each trunk or blade averaging .43 nanometers in diameter. The length is dependent on variables such as the amount of time spent in the high heat environment.

An artistic depiction of a carbon nanotube. | Credit: AJC1 via Flickr, CC BY-SA 2.0

Besides surface analysis, carbon nanotubes have proven invaluable in many research and commercial arenas, their luminescence being only one of many properties that can improve and enable other technologies. Their mechanical tensile strength is 400 times that of steel while only having one sixth the density, making them very lightweight. CNTs also have highly conductive electrical and thermal properties, are extremely resistant to corrosion, and can be filled with other nanomaterials. All of these advantages open up their applications to include solar cells, sensors, drug delivery, electronic devices and shielding, lithium-ion batteries, body armor, and perhaps even a space elevator, assuming significant advances overcome its hurdles.

Next Steps

The nanotube-laced smart skin is ready for scaling up into real-world applications, but its chosen industry may take time to adopt given the general resistance to change in a field with long-standing existing technology. While awaiting embrace in the arena it was primarily designed for, the smart skin has other potential uses in engineering research applications. Bruce Weisman, also the discoverer of CNT fluorescence, anticipates its advantages being used for testing the design of small-scaled structures and engines prior to deployment. Niche applications like these may be the primary entry point into the market for some time to come. In the meantime, the researchers plan to continue developing their strain reader to capture simultaneous readings from large surfaces.

News

Tesla expands Robotaxi geofence, but not the garage

This has broadened its geofence to nearly three times the size of Waymo’s current service area, which is great from a comparative standpoint. However, there seems to be something that also needs to be expanded as the geofence gets larger: the size of the Robotaxi fleet.

Published

35 minutes ago

October 30, 2025

Joey Klender

Credit: Joe Tegtmeyer | X

Tesla has expanded its Robotaxi geofence four times, once as recently as this week.

However, the company has seemingly kept its fleet size relatively small compared to the size of the service area, making some people — even pro-Tesla influencers — ask for more transparency and an expansion of the number of vehicles it has operating.

Over the past four months, Tesla has done an excellent job of maintaining growth with its service area in Austin as it continues to roll out the early stages of what is the Robotaxi platform.

The most recent expansion brought its size from 170 square miles (440.298 sq. km) to 243 square miles (629.367 sq. km).

Tesla sends clear message to Waymo with latest Austin Robotaxi move

Tesla has never revealed exactly how many Model Y vehicles it is using in Austin for its partially driverless ride-hailing service (We say partial because the Safety Monitor moves to the driver’s seat for freeway routes).

When it first launched Robotaxi, Tesla said it would be a small fleet size, between 10 and 20 vehicles. In late August, after its second expansion of the service area, it then said it “also increased the number of cars available by 50 percent.”

Tesla reveals it has expanded its Robotaxi fleet in Austin

The problem is, nobody knows how many cars were in the fleet to begin with, so there’s no real concrete figure on how many Robotaxis were available.

This has caused some frustration for users, who have talked about the inability to get rides smoothly. As the geofence has gotten larger, there has only been one mentioned increase in the fleet.

Trying to book a RoboTaxi in the new geofence and can’t get paired with a car.
Really think Tesla needs to add more cars to the fleet in Austin. Has become tougher and tougher to use the service reliably @elonmusk pic.twitter.com/KHqea3oUxU
— Farzad (@farzyness) October 29, 2025

Tesla did not reveal any new figures or expansion plans in terms of fleet size in the recent Q3 Earnings Call, but there is still a true frustration among many because the company will not reveal an exact figure.

News

Tesla recalls 6,197 Cybertrucks for light bar adhesive issue

On October 20, Tesla issued a voluntary recall of the impacted vehicles and has identified 619 warranty claims and just a single field report that is related to the issue.

Published

2 hours ago

October 30, 2025

Joey Klender

Credit: Francisco Garcia (via Greggertruck on X)

Tesla has recalled 6,197 Cybertrucks for a light bar adhesive issue that was utilized by Service to install the aftermarket part.

According to the National Highway Traffic Safety Administration (NHTSA), impacted vehicles may have had the light bar “inadvertently attached to the windshield using the incorrect surface primer.”

Tesla identified an issue with the light bar’s adhesion to glass back in February and worked for months to find a solution. In October, the company performed chemical testing as a part of an engineering study and determined the root cause as the BetaPrime primer it utilized, figuring out that it was not the right surface priming material to use for this specific application.

On October 20, Tesla issued a voluntary recall of the impacted vehicles and has identified 619 warranty claims and just a single field report that is related to the issue.

The component is manufactured by a Romanian company called Hella Romania S.R.L., but the issue is not the primer’s quality. Instead, it is simply the fact that it is not the correct adhesive for this specific type of application.

Tesla says there are no reports of injuries or deaths due to this issue, and it will be resolved. In the 473 report that the NHTSA released this morning, Tesla said:

“At no charge to customers, Tesla will inspect the service-installed optional off-road light bar accessory for delamination or damage and if either is present, replace the light bar with a new light bar adhered with tape and a positive mechanical attachment. If no delamination or damage is present, Tesla will retrofit the service-installed optional off-road light bar accessory with a positive mechanical attachment.”

This is the third recall applied to Cybertrucks this year, as one on March 18 highlighted the potential for exterior trim panels to detach while driving, and another earlier this month when the NHTSA said its front parking lights were too bright.

Tesla resolved the first with a free assembly replacement, while the headlight issue was fixed with an Over-the-Air software update earlier this week. Owners said there was a noticeable difference in the brightness of the lights now compared to previously.

Investor's Corner

Tesla investor Calpers opposes Elon Musk’s 2025 performance award

Musk’s 2025 pay plan will be decided at Tesla’s 2025 Annual Shareholder Meeting, which will be held on November 6 in Giga Texas.

Published

3 hours ago

October 30, 2025

Simon Alvarez

Credit: Tesla China

One of the United States’ largest pension funds, the California Public Employees’ Retirement System (Calpers), has stated that it will be voting against Elon Musk’s 2025 Tesla CEO performance award.

Musk’s 2025 pay plan will be decided at Tesla’s 2025 Annual Shareholder Meeting, which will be held on November 6 in Giga Texas. Company executives have stated that the upcoming vote will decide Tesla’s fate in the years to come.

Why Calpers opposes Musk’s 2025 performance award

In a statement shared with Bloomberg News, a Calpers spokesperson criticized the scale of Musk’s proposed deal. Calpers currently holds about 5 million Tesla shares, giving its stance meaningful influence among institutional investors.

“The CEO pay package proposed by Tesla is larger than pay packages for CEOs in comparable companies by many orders of magnitude. It would also further concentrate power in a single shareholder,” the spokesperson stated.

This is not the first time Calpers has opposed a major Musk pay deal. The fund previously voted against a $56 billion package proposed for Musk and criticized the CEO’s 2018 performance-based plan, which was perceived as unrealistic due to its ambitious nature at the time. Musk’s 2018 pay plan was later struck down by a Delaware court, though Tesla is currently appealing the decision.

Musk’s 2025 CEO Performance Award

While Elon Musk’s 2025 performance award will result in him becoming a trillionaire, he would not be able to receive any compensation from Tesla unless aggressive operational and financial targets are met. For Musk to receive his full compensation, for example, he would have to grow Tesla’s market cap from today’s $1.1 trillion to $8.5 trillion, effectively making it the world’s most valuable company by a mile.

Musk has also maintained that his 2025 performance award is not about compensation. It’s about his controlling stake at Tesla. “If I can just get kicked out in the future by activist shareholder advisory firms who don’t even own Tesla shares themselves, I’m not comfortable with that future,” Musk wrote in a post on X.