Picture this: you’re making a smoothie and reach out for an apple from your fruit bowl. It looks perfectly fine on the outside. But when you take a bite, yikes! It’s all mushy and spoiled inside. What if there was a way to know that your fruit had gone bad without having to taste it? Enter the magic of perovskite-modified LEDs that promise to reveal the rot in your fruit and veggies before it’s visible. Sounds interesting? Let’s dig in.
A Colorful Solution to a Common Problem
We’re all familiar with LEDs, those tiny shining stars that make our devices glow and our homes sparkle. But what if I told you these little lights could do more than just illuminate? That’s right, LEDs are now playing detective, spotting the spoilage in your food even before you can see it.
This is made possible by perovskite crystals. Now, you might be wondering what a perovskite is. No, it’s not a new type of Pokemon. Perovskites are a group of materials that are excellent at capturing and converting light. They’re relatively simple to produce, highly efficient, and are already making waves in solar cell technology.
How does it Work? The Science Behind the Magic
A regular LED emits light in a rather narrow band. To get the full spectrum of white light produced by the sun, LEDs are often coated with luminescent substances, turning them into what’s known as ‘phosphor-converted’ or pc-LEDs.
When these LEDs are modified with a double perovskite doped with bismuth and chromium, something magical happens. Part of the bismuth component emits warm white light (the kind that lights up your room), and another part transfers energy to the chromium component. This triggers an additional emission in the near-infrared range or NIR.
What’s so special about NIR? Well, it has a neat trick up its sleeve. Food contains water, and water absorbs NIR at around 1000 nm. The more water that is present (as food starts to rot, it retains more water), the greater the absorption of NIR, leading to a darker contrast in an image taken under NIR light. This non-invasive imaging process can estimate the water content in different parts of food, giving us a clear picture of its freshness.
Putting it to the Test – Apples and Strawberries Under the Spotlight
Imagine beaming these modified pc-LEDs on apples or strawberries. What you’ll see is quite extraordinary. Dark spots begin to appear in areas that seem perfectly fine to the naked eye. What you’re witnessing is the LED revealing areas that have started to rot but aren’t yet visible.
Does this mean you’ll need two devices, one for visible light and another for NIR light? While this could make such an instrument a bit pricey for everyday use, the researchers assure us that the pc LEDs are easy to manufacture without any chemical waste or solvents. The initial cost could be more than recovered by the long service life and scalability of this ingenious dual-emitting pc-LED device.
The Future of Food Inspection
Picture a compact device that scans your fruits and vegetables, revealing their true condition under the bright light. Not only would this save you from the unpleasant surprise of biting into a rotten apple, but it could also have wide-reaching implications for food waste reduction and quality control in the food industry.
A Bright Future Ahead
Who knew that LEDs, those tiny points of light we see everywhere, could hold such potential? From illuminating our lives to keeping an eye on the freshness of our food, LEDs are proving that they have more to offer than meets the eye. The next time you look at an LED, remember, it’s not just a source of light, it might also be your new food quality detective. So, are you ready to see your fruit bowl in a new light?
Sajid Saikia, Animesh Ghosh, Angshuman Nag. Broad Dual Emission by Codoping Cr3+ () and Bi3 () in Cs2Ag0.6Na0.4InCl6 Double Perovskite. Angewandte Chemie International Edition, 2023; Link
