Have Your VR and Eat It Too

Some aspects of virtual reality (VR) have advanced to the point where they are pretty convincing. The visuals and sounds in virtual environments, for instance, are now highly immersive and can really draw users in. But the situation is not nearly so good when it comes to the other senses. When elements that require the reproduction of the sensations of touch, smell, or taste appear in a virtual environment, the illusion of reality will quickly fade away.

Researchers at The Ohio State University recently decided to tackle perhaps the least developed of these virtual senses — taste. While previous efforts have been made to simulate taste digitally, they have largely fallen short of the goal. Most current solutions rely on electrical or thermal stimulation of the tongue, which can only replicate a limited range of taste sensations. Others attempt to use chemical releases, but these methods often struggle with precision, reliability, and integration with existing VR systems. Furthermore, most such interfaces are bulky and uncomfortable, making them impractical for real-world use.

In an effort to overcome these challenges, the researchers developed a bio-integrated gustatory interface called “e-Taste.” This system allows users to experience taste sensations remotely by transmitting chemical signals over the Internet. Unlike previous attempts, e-Taste focuses on delivering actual taste compounds to the user in a controlled and programmable way, allowing for a more accurate and immersive experience.

Operation of e-Taste involves a sensing platform that captures taste information and transmits it digitally. This data is then received by a compact electromagnetic (EM) actuation system, which delivers edible taste chemicals to the user through a microfluidic interface. The key to the system’s effectiveness is its hydrogel-based electro-responsive interface, which precisely controls the release of taste chemicals such as glucose (sweet), citric acid (sour), NaCl (salty), MgCl₂ (bitter), and glutamate (umami). By varying the concentration and combination of these chemicals, the system can simulate a wide range of flavors.

The EM actuator consists of a microfluidic channel, a polydimethylsiloxane liquid chamber, permanent magnets, and a coil. The system operates using a bipolar junction transistor as an on/off switch controlled by an ESP32 microcontroller. When activated, the coil generates an alternating magnetic field, causing the diaphragm in the liquid chamber to deform and pump the solution through the microfluidic channel. The duration and frequency of these pulses determine the concentration of taste chemicals, ensuring precise taste replication.

To test the effectiveness of e-Taste, the team conducted field trials with human participants, evaluating their perception of taste intensities and combinations. The results showed that the system could successfully recreate different taste sensations in a controlled and repeatable manner. Participants were able to distinguish between various taste profiles, demonstrating the system’s ability to provide a convincing digital tasting experience.

The development of e-Taste could help to bring about more immersive virtual experiences in the future. By integrating taste into VR, users could one day enjoy virtual dining experiences, or even experience taste-based interactions in gaming and education. But before we get to that future, further research will be needed to refine the technology and expand the range of flavors that can be simulated.