Digital Lollipop: Studying Electrical Stimulation on the Human Tongue to Simulate Taste Sensations

Among the five primary senses, the sense of taste is the least explored as a form of digital media applied in Human--Computer Interface. This article presents an experimental instrument, the Digital Lollipop, for digitally simulating the sensation of taste (gustation) by utilizing electrical stimulation on the human tongue. The system is capable of manipulating the properties of electric currents (magnitude, frequency, and polarity) to formulate different stimuli. To evaluate the effectiveness of this method, the system was experimentally tested in two studies. The first experiment was conducted using separate regions of the human tongue to record occurrences of basic taste sensations and their respective intensity levels. The results indicate occurrences of sour, salty, bitter, and sweet sensations from different regions of the tongue. One of the major discoveries of this experiment was that the sweet taste emerges via an inverse-current mechanism, which deserves further research in the future. The second study was conducted to compare natural and artificial (virtual) sour taste sensations and examine the possibility of effectively controlling the artificial sour taste at three intensity levels (mild, medium, and strong). The proposed method is attractive since it does not require any chemical solutions and facilitates further research opportunities in several directions including human--computer interaction, virtual reality, food and beverage, as well as medicine.