A study on sensitivity, reproducibility, and stability of sourness and saltiness taste sensors using a mixture of lipid membranes

Our study successfully fabricated sourness and saltiness sensors and investigated the response toward acetic acid and sodium chloride as the sourness and saltiness sample solutions, respectively. The sensors were made using a lipid membrane with a mixture of two materials. The fabricated sensors can detect the concentration of a small amount of 0.03 mM for the sourness sensor and 0.316 mM for the saltiness sensor, much lower than the human tongue threshold. Moreover, the sensors show a directly proportional response for both sourness and saltiness sensors in the range of 0.03–3 mM of acetic acid and 0.316–31.6 mM of sodium chloride, respectively. The interaction between positive charge in the lipid membrane and anionic species in the sample solution was believed to be the sensing mechanism in this research. Both sensors were refabricated three times, and the saltiness sensor exhibited a similar response when exposed to 3.16 mM of sodium chloride, while the sourness sensor still has to improve its reproducibility. In addition, the fabricated sensors were also tested on three consecutive days to observe the stability.