Scientists have made a virtual “lollipop” to transmit taste over the Internet

Virtual reality not only aims to provide the ability to experience presence and enjoy unusual sights and sounds, it also intends to convey smells and tastes. If you immerse yourself, then in full, although with tastes everything is still very difficult. We need to come up with a convenient interface to influence the receptors of the tongue. Scientists from Hong Kong believe they have found the perfect solution.

Image source: City University of Hong Kong

Basically, taste sensations are transmitted through special receptors on the tongue. There are four basic tastes – sweet, salty, sour and bitter. In recent years, a fifth taste has become fashionable – common in Japan and nearby, which is called umami. If we move away from fashion, experts tend to believe that the tongue also recognizes a spectrum of fats, which is also perceived by humans as a pleasant taste.

It has been proposed to irritate the receptors on the tongue in different ways: chemical, thermal, electrical stimulation, as well as iontophoresis. The chemical method is closest to the natural one and is accompanied by the application of flavored substances directly to the tongue. But this method is not well suited for virtual reality, as it suffers from delays and the need to store considerable volumes of substances.

Thermal stimulation is based on direct stimulation of the tongue receptors. The problem with it is different – in organizing a compact platform with temperature control, heating and cooling. Electrical stimulation seems to be the best way to imitate tastes – the effect is created by changing the frequency, intensity and direction of electrical signals supplied to the receptors. The limitation is the need to place something like patches on the tongue, which is inconvenient in many cases.

Therefore, a group of scientists from the City University of Hong Kong chose iontophoresis as a method of stimulating receptors on the tongue, which achieves stable taste feedback by using ions passing through biologically safe hydrogels to transport aromatic substances.

A lollipop simulator was chosen as the interface. The system is wireless, works via Bluetooth. The “lollipop” is 3D printed from nylon. Its dimensions are 8 × 3 × 1 cm and its weight is 15 g. It contains nine channels for transmitting flavor ions to the tongue. The device is loaded with agarose-based solutions. It is a kind of hydrogel containing chemically synthesized flavors that mimic sugar, salt, citric acid, cherry, passion fruit, green tea, milk, durian and grapefruit. Under the control of a computer interface, ions are supplied to the tongue through a volume of hydrogel with one or another taste or a mixture of them.

Adding smell—seven specific chemicals—to the mixture further enhances taste perception. Future research will focus on extending the device’s use time, which is currently limited to about an hour as chemically flavored hydrogels dry out and lose flavor.

According to the developers, the virtual “lollipop” can help teach children about food. It can also become a universal sensor for detecting taste disorders in patients. Finally, the device will help you discover food flavors online without having to taste real samples.