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The screen you’re reading this on is covered with tiny structures — here’s how it works

Seemingly smooth surfaces are often covered in microscopic structures, and for very good reason.

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You’re reading this on a backlit screen. Maybe it’s a laptop, or a tablet, or a smartphone. And thanks to a teeny tiny world of structures embedded in the screen, it’s brighter than ever. This repeating pattern of groove-like structures redirects the light so it doesn’t scatter all over the place and instead travels directly to you, saving battery life. This pattern is created by a process called microreplication. And the microscopic structures involved can change the physical, chemical, and optical properties of a variety of surfaces. Microreplication has gone on to improve upon everything from light reflection to functional abrasives to the movement of fluids. What a surprise, then, that such precise technology actually started with one of the clunkiest of classroom staples — an overhead projector.

Believe it or not, the projector from your history class used to be even heavier, until microreplication came around.

In the late 1950s, 3M scientist Roger Appeldorn was tasked with making overhead projectors lighter, cheaper, and simply better. At the time, the projector’s lens was made of a heavy glass first developed in the 1800s to focus the light sent out by lighthouses. After much tinkering and research — and some inspiration from the grooves in vinyl records — Appeldorn realized he could make the same lens with plastic if it had repeating, identically structured surfaces on it. These structures, invisible to the naked eye, would number in the hundreds per inch to direct light in an efficient beam. He and his team developed a prototype for a new projector by 1962.

Today, tiny replicated structures on plastic film are used for all sorts of light-reflecting needs, like electronic screens, road signs on dark streets, and even a NASA satellite with a more cost-effective solar lens array. The process has also been used to improve sandpaper and other abrasives; rather than being made up of particles of varying size and sharpness, these tools can instead use repeated particles of the same size and sharpness so they’re more effective in cutting. It’s even been applied to golf gloves, jackhammers, wheelchairs, and more; the structures act like mini hands and fingers to produce a gripping ability that maintains control over movement.

Scientists have taken this tiny technology to the next level: health care research.

So, where is microreplication headed? Now it’s front and center on the future of health care. In 2000, 3M scientists developed patches of hundreds of tiny needles, or microneedles, that extract blood to measure sugar levels in people with diabetes. Over the last decade, they reversed the concept of taking fluids out so that now microneedle patches can also inject critical vaccines and other drugs. The replication of tiny needles onto a surface the size of a dime has made both the measurement and immunization processes nearly painless — a huge step forward for the 10 percent of patients who are afraid of needles. And the system has been made simple enough for patients to administer on their own.

Now, microneedles are being used to deliver a trial therapeutic cancer vaccine directly through the skin. These microreplicated needles are not only relatively painless, consistent, and easy to use, but studies point to a better immune response than intramuscular injections. That means they could improve results and therefore reduce healthcare expenses; in a world where cancer costs patients over $1 trillion, this is no small feat.

Microreplication has grown into an invisible wonder. Zoom in for a closer look in the video above.

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