Today's KNOWLEDGE Share: Frozen smoke’ sensors detect toxic air in our offices and homes

Today's KNOWLEDGE Share

Researchers from the University of Warwick and the University of Cambridge have developed sensors made from frozen smoke. They claim the sensors can detect extremely low concentrations of formaldehyde.

Significantly, the results may contribute to a new era of air quality monitoring. 

Formaldehyde — what is it?

Formaldehyde is a commonly found air pollutant in indoor environments. Household items like wallpapers, pressed wood products, paints, and tobacco smoke emit it.High concentrations of formaldehyde exposure can lead to respiratory irritation, headaches, respiratory symptoms, and an increased risk of certain cancers.Current indoor air quality sensors lack the sensitivity to detect formaldehyde at such low levels. This is what the researchers focused on. 

The team used 3D printing techniques to develop sensors made from aerogels, also known as frozen smoke. These sensors can detect extremely low levels of formaldehyde in indoor air, which the researchers tested for. 

Aerogels are frozen smoke

Frozen smoke is an apt name for aerogels due to their see-through appearance.These materials exhibit low density, which can be as low as a thousandth of traditional solids, and their highly porous nature.Aerogels are 99.8 percent air, with a network of interconnected nanoparticles forming a highly porous structure, and they possess a high surface area. These properties make aerogels a great candidate for gas-sensing applications.

Their unique structure provides ample sites for gas molecules to interact, improving sensitivity.Through 3D-printing, researcher can tailor aerogels, allowing for precise control over sensor design.

This also helps enhance performance when detecting formaldehyde and other gases at low concentrations.For this, the researchers chose tin dioxide (SnO2), a semiconductor material with excellent sensing properties (especially formaldehyde), allowing for detection even at low concentrations.

3D printing of a hybrid material:

While SnO2 is excellent at detecting formaldehyde at low concentrations, the researchers wanted to enhance it.

They began by creating SnO2 quantum dots using soap-like substances to help with high-pressure, high temperature process. In the paper, the researchers describe this as a ‘surfactant-assisted hydrothermal growth process.’

During this stage, SnO2 mixes with a surfactant to control the size and shape of the resulting nanoparticles.The hot water conditions promote the growth of SnO2 nanoparticles into quantum dot structures with uniform size and distribution.In the next step, the team evenly distribute SnO2 quantum dots on graphene oxide (GO) sheets dispersed in a solution. This serves as the ink for the 3D printing process.

For gas sensing applications, the scientists 3D-print the aerogels on printed circuit board (PCB) substrates in meander (or zig-zag) shapes.The researchers then dope these sensors with metal salt solutions, resulting in a hybrid material: SnO2/rGO 0D-2D material–based aerogels.

Here, the rGO is reduced graphene oxide, which offers high electrical conductivity and large surface areas.This enhances the sensor’s sensitivity and response and also improves the material’s mechanical strength and stability.Next, the combination of quantum dots combined with the SnO20D for 0D (or 0-dimensional) materials. This further enhances the sensing capabilities of the aerogel.

More importantly, their small size allows for precise tuning of electronic properties, enabling selective detection of formaldehyde molecules amidst other gases.

Metal doping introduces additional functionalities to the sensor material. These metal ions can modify the electronic structure of SnO2/rGO, enhancing its sensing performance by increasing sensitivity, selectivity, and stability.

And the 2D or 2-dimensional material is the graphene sheet.

Improving with machine learning

Further, the researchers developed a gas species recognition algorithm based on dynamic feature extraction.They used machine learning algorithms to classify different gases based on their features accurately.This allowed for real-time sensing and recognition, even without reaching a steady state in the sensing response.The sensor achieved a record-high response of 15.23 percent for 1 part per million formaldehyde concentration and an ultralow detection limit of 8.02 parts per billion.

The findings of the study are published in Science Advances.

source:Interesting Engineering

Clariant and Lummus Technology Awards Contract for Catalyst Technology in China

Clariant and its process partner Lummus Technology have been selected by Huizhou Boeko Materials to provide their CATOFIN catalyst and process technology for the dehydrogenation of isobutane at the new plant in Huizhou City, China.

The process technology is exclusively licensed by Lummus Technology, while the tailor-made catalyst is supplied by Clariant. It is the first time Huizhou Boeko will license the CATOFIN technology at one of their sites.

Yielding Superior Annual Production Output:

The scope of the current award includes the technology license and basic engineering. Once complete, the plant will produce 550,000 metric tons per annum (MTA) of net isobutylene. It will serve as feedstock for the downstream production of methyl tertiary butyl ether (MTBE).

The highly efficient CATOFIN process uses fixed-bed reactors and operates at optimum reactor pressure and temperature to maximize catalytic dehydrogenation of isobutane for high yields of isobutylene at low investment and operating costs.

“We are delighted to deliver our industry leading CATOFIN catalyst to this first Huizhou Boeko plant and look forward to a fruitful partnership. CATOFIN offers excellent reliability and productivity, yielding superior annual production output, which in turn leads to increased overall profitability for the plant,” said Jens Cuntze, business president catalysts and APAC at Clariant.

New Plant Ensures Customer Proximity and Covers Increasing Demand

Since its commercial launch in 2017, CATOFIN has been selected for 39 new projects around the world. More than 50% of these plants are located in China. To meet the rapidly increasing demand of customers like Huizhou Boeko in the region and to ensure close proximity, Clariant recently opened a new CATOFIN catalyst plant with significant production capacity in Jiaxing, Zhejiang Province, China in April 2023.

Source: Clariant/omnexus.specialchem

CRP Technology to Exhibit Composite-based Orthoses at SuperPower Design Exhibition

CRP Technology's 3D printed orthoses made of glass-fiber reinforced thermoplastic, Windform® GT material, have been selected to be exhibited at the SuperPower Design exhibition. The event will be held from March 24 to August 25, 2024 at the Center for Innovation and Design (CID) in Grand-Hornu, Belgium.

An orthosis is a medical device applied externally to the human body. It is used to assist, restrict, control, or limit movement for specific body segments.

Integrated Framework of Mass Customization for Orthoses:

The orthoses that will be showcased in Belgium include one leg orthosis for drop foot and one hand orthosis. They were created and manufactured using an innovative approach and procedure. CRP Technology and MHOX, in collaboration with medical professionals, developed an integrated framework of mass customization for generative orthoses. The system is based on three phases: bodyscan of the patient, generation of a 3D model of the orthosis, and 3D printing of the orthosis. It aims to replace the traditional sizing system with a complete customization of the product.

MHOX handled the first two stages by developing and using proprietary software, which was designed for the automated management of systems for mass product customization.

The third stage was assigned to CRP Technology. They 3D printed the orthoses with their Windform® GT material by means of Selective Laser Sintering. Windform® GT is a polyamide-based material reinforced with glass fiber. Its special features, such as elasticity, flexibility, impact resistance, impermeability, and durability, make it particularly suitable for applications where the material has to flex for extended periods without the risk of damage. These characteristics are crucial for the manufacturing of generative orthoses, where reliability, performance, and longevity are essential considerations.

3D printed orthoses in Windform® GT represent a compelling example of how design and technology can intersect to create innovative solutions that push the boundaries of human potential. This makes them a fitting addition to the SuperPower Design exhibition.

Source: CRP Technology/Omnexus.specialchem.com

Today's KNOWLEDGE Share:128-Cavity Mold

Today's KNOWLEDGE Share

World First: Manufacturer Runs 128-Cavity Mold in 1.9-second Cycle Time

A 128-cavity mold will produce 26-mm water closures in a cycle time of 1.9 seconds in a live experience at Netstal’s booth at NPE 2024.

Netstal’s CAP-Line 4500 is identical to two production systems being used by Alltrista, a contract manufacturer based in Greer, SC. The line features an all-electric clamping unit with 4,500 kN of force and a dry cycle time of 1.4 seconds. An optimized barrier screw allows for a smaller injection unit with higher plasticizing performance and better homogenization, Netstal expained.

More than three billion closures produced annually

"Alltrista is the first in the world to produce with 128 cavities and a cycle time of 1.9 seconds,” said Horst Kogler, head of Netstsal’s caps and closures business unit. “They produce more than 3.1 billion closures with two lines [annually]. More output per square meter of production area is currently not possible."

Enclosure weight reduced 25%:

The mold, produced by Austria’s z-moulds, is as small and light as a 96-cavity mold and fits into the injection molding machine with a smaller column distance. Cycle time is reduced by the smaller design, which also requires moving less mass. Alltrista has cut the weight of its enclosures by 25%; with 3.1 billion closures produced annually, that means more than 2 million pounds less resin used – about the weight of 160 African Bush elephants, the company said.

In the NPE demonstration, finished caps will travel through an Intravis vision-inspection system. The system executes 360-degree inspection of the closures to an accuracy of hundredths of a millimeter using nine high-resolution cameras. 

Overall, Netstal’s CAP-Line also fits in a smaller overall space — 538 square feet — and uses about 12% less electricity than competing machines running 96-cavity molds, Kogler said.

Accelerated machine delivery times

"With the new CAP-Line concept, we are aligning our portfolio even more closely with our customers' applications,” he noted. “Closure manufacturers benefit from a customized system, while pre-configuration can speed up the consultation and quotation process so that delivery times for the machine are as short as possible."

Added Christopher Navratil, CTO of Alltrista's parent company: "We were determined to be the first manufacturer to run a system with 128 cavities in under two seconds. In Netstal, z-moulds, and Intravis, we have found the best system partners for this project. Each company is a leader in its field, and the combination is unbeatable. With our 128-cavity systems, we produce more efficiently than ever before, can deliver at any time, and inspire our customers. This has given us an enormous competitive advantage."

Visit Netstal at booth W223 during NPE2024 at the Orange County Convention Center in Orlando, FL, from May 6 to 10.

source:Geoff Giodano (plasticstoday)

Elusive 3D printed nanoparticles could lead to new shapeshifting materials

In nanomaterials, shape is destiny. That is, the geometry of the particle in the material defines the physical characteristics of the resulting material.

“A crystal made of nano-ball bearings will arrange themselves differently than a crystal made of nano-dice and these arrangements will produce very different physical properties,” said Wendy Gu, an assistant professor of mechanical engineering at Stanford University, introducing her latest paper which appears in the journal Nature Communications. “We’ve used a 3D nanoprinting technique to produce one of the most promising shapes known – Archimedean truncated tetrahedrons. They are micron-scale tetrahedrons with the tips lopped off.”

In the paper, Gu and her co-authors describe how they nanoprinted tens of thousands of these challenging nanoparticles, stirred them into a solution, and then watched as they self-assembled into various promising crystal structures. More critically, these materials can shift between states in minutes simply by rearranging the particles into new geometric patterns.

This ability to change “phases,” as materials engineers refer to the shapeshifting quality, is similar to the atomic rearrangement that turns iron into tempered steel, or in materials that allow computers to store terabytes of valuable data in digital form.

“If we can learn to control these phase shifts in materials made of these Archimedean truncated tetrahedrons it could lead in many promising engineering directions,” she said.

Elusive prey

Archimedean truncated tetrahedrons (ATTs) have long been theorized to be among the most desirable of geometries for producing materials that can easily change phase, but until recently were challenging to fabricate – predicted in computer simulations yet difficult to reproduce in the real world.

Gu is quick to point out that her team is not the first to produce nanoscale Archimedean truncated tetrahedrons in quantity, but they are among the first, if not the first, to use 3D nanoprinting to do it.

“With 3D nanoprinting, we can make almost any shape we want. We can control the particle shape very carefully,” Gu explained. “This particular shape has been predicted by simulations to form very interesting structures. When you can pack them together in various ways they produce valuable physical properties.”

ATTs form at least two highly desirable geometric structures. The first is a hexagonal pattern in which the tetrahedrons rest flat on the substrate with their truncated tips pointing upward like a nanoscale mountain range. The second is perhaps even more promising, Gu said. It is a crystalline quasi-diamond structure in which the tetrahedrons alternate in upward- and downward-facing orientations, like eggs resting in an egg carton. The diamond arrangement is considered a “Holy Grail” in the photonics community and could lead in many new and interesting scientific directions.

Most importantly, however, when properly engineered, future materials made of 3D printed particles can be rearranged rapidly, switching easily back and forth between phases with the application of a magnetic field, electric current, heat, or other engineering method.

Gu said she can imagine coatings for solar panels that change throughout the day to maximize energy efficiency, new-age hydrophobic films for airplane wings and windows that mean they never fog or ice up, or new types of computer memory. The list goes on and on.

“Right now, we’re working on making these particles magnetic to control how they behave,” Gu said of her latest research already underway using Archimedean truncated tetrahedron nanoparticles in new ways. “The possibilities are only beginning to be explored.” Reference Direct observation of phase transitions in truncated tetrahedral microparticles under quasi-2D confinement

David Doan, John Kulikowski & X. Wendy Gu

https://www.nature.com/articles/s41467-024-46230-x