78 CHEMICAL SENSORS. VOLUME 6: CHEMICAL SENSORS APPLICATIONS may be leakage of recognition elements from the membrane and slow equilibration between the sensor surface and the surroundings. Specific reasons for the VET may be oxide-layer formation or reorganiza- tion of the active surface on the working electrode. For some electrode materials (e.g., gold), poisoning due to exposure to sulfur-containing compounds may occur. Several solutions to signal drift problems have been introduced. The taste sensing system of the Anirutsi company (as described in Section 6) washes and calibrates the electrodes between measure- ments, which is an often-used solution to drift problems in analytical chemistry. For the VET, a polish- ing step can be used to regenerate the sensing surface between measurements (See Section 4.2.1.). 6. COMMERCIALIZATION The taste sensing system originally developed by Toko et al. (1990) was commercialized in 1992 by Anirutsi (Taste Sensing System SA401, Anritsu Corp., Japan). The system consists of an eight-channel multisensor placed on a robot arm, controlled by a computer. The tested samples are placed in sample holders that also contain cleaning and reference solutions. A measurement sequence starts with a clean- ing step in which the multisensor is introduced to the cleaning solution, thereafter into the sample solu- tion, and the cycle repeats. The multisensor is introduced to the reference solution at certain intervals for calibration purposes.