Development of the Sensor Part Re-composition on the Salivary NO 3 − Measurement Device for the Evaluation of Mental Workload *

We have been developed the salivary NO 3 − measurement device which gives quantitative values of human mental workload from only one-drop saliva. We think this device help people in maritime societies, especially navigators, to reduce their mental workload on duties. In this paper, we introduce 2 systems: the physiological response system using salivary NO 3 − as a helpful physiological index, and the recomposed sensor system which improves the sensor part of a conventional salivary NO 3 − measurement device. In addition, we introduce one example of experimental results in a ship-simulator where we use the improved salivary NO 3 − measurement device. We acknowledge that the evaluation of mental workload by the conventional salivary NO 3 − measurement device is effect through on-board experiments and ship-simulator experiments. As a result, this conventional device is the good physiological index, however, it has a problem. The sensor of the salivary NO 3 − measurement device is the ion-sensitive field-effect transistors, which have the drift characteristic giving a noise to the measured values. So far, we have solved the drift problem by calibrations before every measurement. This time we fundamentally solve this drift problem to re-compose a new sensor on the salivary NO 3 − measurement device. Through ship-simulator experiments, we validate the effectiveness of the new salivary NO 3 − measurement device with the new sensor.