Apparently Touchscreens Can Now Detect and Identify Pastries

New research shows that your tablet can be used to sense and recognize pastries, which opens up a whole range of sweet possibilities!

Cameron Coward
3 years agoFood & Drinks / Displays / Sensors

If you’re old enough to have been subjected to touchscreens before the iPhone came around, then you know how terrible they used to be. The vast majority of them were resistive touchscreens, which meant that you could only use them with a stylus. Even then, they were horribly inaccurate and unresponsive. Today’s capacitive touchscreens, like those on your smartphone and tablet, are far better, with the ability to detect multiple touch points with remarkable accuracy and speed. Because they’re capacitive, they can detect anything that is conductive. As Dr. Florian Heller discovered, that apparently means that your iPad can even detect your pastries, which opens up a whole range of sweet possibilities.

Capacitive touchscreens and capacitive buttons work because you’re a moist meat sack that conducts electricity. You may not be as good of a conductor as a nice copper wire, but you’re definitely better than the surrounding air. A touchscreen is lined with a thin matrix of traces that connect to a microcontroller that measures capacitance. When you touch your finger to the screen, it gets close enough to that matrix to alter the capacitance at that point in the matrix and a press is registered at the corresponding coordinates. Multi-touch capacitive touchscreens can detect multiple points. If the screen can detect enough points, a rough touch map can be generated. That is how you iPad can differentiate between the palm of your hand and a stylus when you’re drawing.

That same idea is being used here, but to detect baked goods. As long as your muffin isn’t completely dried out, it will be slightly conductive. Placing it on a capacitive touchscreen will create a “map” of points similar to when you rest your palm on your tablet. By itself, that would only be enough to give you an extremely rough estimate of the shape of a croissant or bagel. But if the pastries are baked specifically with this in mind, identifiable patterns can be created. In an example from Heller, baking wafers on the bottom of muffins are used to “shield” part of the muffin dough. That leaves muffin contact points in a specific pattern that can be detected. By changing the shape of the wafers, multiple unique patterns can be created that can then be used to identify the pastry in question. It’s a bit like scanning a QR code with your smartphone, but with a far lower resolution.

That’s interesting, but probably not all that useful at first glance. You already know that you have a delicious donut in front of you and you don’t need your tablet to tell you so. But if more information could be encoded in the contact points, they could be used to identify specific products. That, in turn, could be used to serve you with information like calorie content. The conductivity of the pastry, relative to others, could also be used for identification. Frankly, however, that seems a little far-fetched to me. I can’t imagine anyone actually plopping a cookie down onto their tablet in order to find out information about it that is already listed on the package, but it is certainly fun to think about.

Cameron Coward
Writer for Hackster News. Proud husband and dog dad. Maker and serial hobbyist.
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