Fig. 8. Sensor performances of the basic bitterness sensor [29]. (a) CPA values of response to six taste substances. (b) Relationship between results of CPA values of the basic bitter substances and human sensory score. The bitter substance materials: 0.1 mM of hydrochloride salts. Data are expressed as mean ± SD (n = 4). All samples include 30 mM KCl and 0.3 mM tartaric acid as a supporting electrolyte.