Researchers at the City University of Hong Kong have developed a new interface to simulate taste in virtual and other extended reality (XR). The lollipop-shaped lickable device can produce nine different flavors: sugar, salt, citric acid, cherry, passion fruit, green tea, milk, durian, and grapefruit. Each flavor is produced by food-grade chemicals embedded in a pocket of agarose gel. When a voltage is applied to the gel, the chemicals are transported to the surface in a liquid that then mixes with saliva on the tongue like a real lollipop. Increase the voltage and get a stronger flavor.
Initially, the researchers tested several methods for simulating taste, including electrostimulating the tongue. The other methods each came with limitations, such as being too bulky or less safe, so the researchers opted for chemical delivery through a process called iontophoresis, which moves chemicals and ions through hydrogels and has a low electrical-power requirement. With a 2-volt maximum, the device is well within the human safety limit of 30 V, which is considered enough to deliver a substantial shock in some situations.
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