Driving the Future of Technology with Glass
New applications can provide insight into the current state of glass technology and where it might go next.
Humans have been making glass for more than five millennia, and we’ve been using naturally occurring glass in the form of obsidian for even longer. In recent history, glass has found a home in agriculture, energy production, architecture, transportation, semiconductors and many other industries. Because of its material properties, glass continues to appear on the forefront of scientific research, a remarkable track record for a material that’s been around since the Stone Age.
Today, engineers searching for glass materials suitable for a new technology are met with a dizzying array of choices. Advances in glass research have kept pace with the speed of science and consumer technology. From space telescopes that can withstand extreme temperature swings to smartphones, there is no shortage of specialized uses for glass materials.
A review of every recent glass advance isn’t possible in this space. On average, 5,500 articles about glass have been published in academic journals each year for the past five decades. However, a few new applications can provide insight into the current state of glass technology and where it might go next.
Neutron Guides Further Research
Neutrons—one of the three atomic particles—can be deployed in highly sensitive imaging systems that can be used to define the structure of protein molecules. Much like X-rays, these systems measure the absorption and scattering of neutrons as they come into contact with an object—but neutrons are difficult to control. Once generated, they fly in every direction and can only be guided along exceptionally smooth channels; even then, the neutrons must come into contact with the surface at extremely shallow angles.
Engineers looking to develop neutron guides at major research labs might turn to float glass for those channels. In neutron guides, float glass is the ideal substrate for the supermirrors that make up neutron guides, which must feature a roughness of less than one nanometer.
SwissNeutronics recently developed a method of coating float glass’ mirror-smooth surface with over 10,000 layers of nano-thin reflective materials to better guide neutrons. In one case study, the use of nano-coated super mirrors for neutron guides resulted in a six-fold increase of available neutrons.
This improved glass technology is advancing the quality of neutron research and its incredible array of cutting-edge applications. It allows scientists to better understand the materials used in lithium batteries and hydrogen fuel cells, paving the way to zero-emissions cars. It can help identify materials that might be useful in the construction of next-generation computing systems. Neutron imaging can also create detailed, three-dimensional images of solid, even metallic objects to detect extremely small imperfections in manufacturing processes. With better quality glass and coatings, research possibilities expand dramatically.
High Index Glass for Augmented Reality
Augmented reality (AR) glasses have come a long way—in both style and popularity. Many Silicon Valley tech companies are racing to develop the first pair of breakout smart glasses that superimpose digital information on the real world. IDC projects approximately 68 million AR units will be sold in 2022, mimicking the early years of the iPhone, as consumers and organizations find any number of business, education, and entertainment applications for smart glasses.
Technical glass with highly specific optical properties will play a key role in the development of AR optical systems, and most of the efforts to develop consumer-grade smart glasses focus on waveguide technology. With this method, a projector transmits light in red, blue, and green, each passing through a wafer-thin waveguide that reflects the light into the eye with a series of optical gratings, creating an image.
The materials used in a waveguide must satisfy a number of requirements. If the materials are too heavy, for example, users may find the unit uncomfortable. More importantly, the glass wafers used must have specific optical properties. Most early smart glasses had an extremely limited field of view, which meant that the digital imagery could only be rendered over a relatively narrow range of the user’s vision.
Optical glass might seem like an ideal material to solve the field-of-view challenges, since there is a wide selection of candidate materials with well-known refractive indices, but it’s too heavy and difficult to turn into wafers. A semiconductor substrate satisfies the weight requirement and is widely available. In fact, some AR prototypes use these substrates because they’re the most widely available wafer glass. The chemistry of the substrate material, however, is incompatible with a high-refractive index.
AR hardware developers have been looking for a special kind of glass to support waveguides, and they finally found it in recently developed ultra-thin glass that has a refractive index of up to 2.0. That index is enough to more than double the field of view of existing prototypes, and the material is lightweight, which translates into increased user comfort. Another added benefit is the glass is highly homogeneous, resulting in very bright projected images.
Already, factories use AR to train workers in new processes. Workers making jet planes reference AR systems to install complex wiring harnesses without having to page through a manual. In the future, AR could offer turn-by-turn directions while driving. Consumer-grade AR might allow us to engage in multi-day games of capture the flag, with millions of people on either team. For any of this to happen, AR glasses still must overcome a number of challenges, but high-tech glass innovations are taking us one step closer.
Ultra-Thin Glass License Plates for Drones
Commercial drones are expected to create 100,000 jobs by 2025. Their pilots will deliver medicine to patients at home, aid farmers in surveying crops, inspect power lines and other infrastructure, and more. The increasing use of drones has led regulators across the globe to demand that drones be both registered and labeled so that owners can be identified should a drone crash, enter restricted airspace, or otherwise create danger for aircraft, buildings, and people below.
The challenge to drone labeling is that it must be able to withstand high temperatures. For instance, temperatures from lithium ion batteries, which provide the power supply to most of today’s drones, can reach above 660°C. That’s hot enough to melt aluminum, the most likely candidate for a drone license plate, which would make identification far more difficult.
Roboterwerk, a German company, took a different route and used ultra-thin glass to develop a glass-titanium-carbon compound for drone license plates. The plates are lightweight and flexible, but can withstand temperatures of up to 870°C and feature very high mechanical strength. The glass license plates also don’t interfere with signals and sensors the way metals would. Drone labeling that is fireproof and resilient will help foster an industry that is accountable and trackable, helping to build trust between the commercial drone industry and the community.
Material Properties Propel New Uses
Glass has long been selected for myriad applications because of its obvious material properties: its transparency, insulating capabilities, and impermeability to liquid and gas. These successes have given way to different demands.
Glass-ceramics’ low coefficient of thermal expansion, for example, makes them suitable for space-based telescopes. Optical glasses that filter all but a narrow band of infrared light are now found in the LIDAR systems of autonomous cars. In the pharmaceutical industry, specialty glass helps limit the risk of interaction between a drug and its container. Fire-rated glass resists heat in burning buildings to allow occupants a safe exit.
As it has for thousands of years, glass will continue to advance technologies and industries with its versatility and unique properties. Who knows where it will take technology next.
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