A Soft and Flexible Artificial Tongue for Pungency Perception.

Artificial tongues have been extensively studied to detect the five basic tastes like humans. Spiciness, or pungency, is essential for food selection for both humans and animals. However, it is challenging to fully mimic human tongue-like performance for spicy taste. Inspired by the fact that milk can relieve the pungent taste on the tongue, we introduced a soft gel-based artificial tongue as a flexible chemiresistive sensor for pungency detection. When exposed to pungent compounds, it leads to the formation of hydrophobic complexes and conformational changes that decrease the ionic conductivity. The artificial tongue enables pungent compounds to be detected over a wide range (0.0001-1 wt %) with high sensitivity (0.259 wt %-1) and fast response times (<10 s). Moreover, our artificial tongue can detect the pungency degree in a variety of spicy foods and condiments with intertranslatable ionic currents. Our work could enable both pungent compound detection and spicy sensation estimation, making a powerful platform for future applications involving movable humanoid robots and portable spicy taste monitoring devices.