Application of Polymer-Based Nitrate Ion-Sensitive Field-Effect Transistors to On-site Measurement of Mental Workload

The primary aim of our research is to complete physiological index to evaluate mental workload. We focus on salivary NO3- as an index, which is emitted to blood vessels from vascular endothelial cells when a human body receives mental workload. The development of a device to measure NO3- in vascular endothelial cells is thus required for the evaluation of mental workload. The device developed here is composed of field-effect transistors and ion-selective membranes. We have adopted a polymer for use with an ion-selective membrane. Two experiments were performed to verify the drift in the device characteristics and to validate the characteristics of the polymer as the ion-selective membrane. Verified experimental results indicated that the polymer was useful as ion-selective membrane material, which has less drift characteristics for a long time measurement. Validated experimental results indicated that NO3- device with new polymer KP-13 has the effectiveness of measurement of mental workload on the spot, compared with values from NO3- device with KP-13 and other physiological indices

Fully Transparent, Ultrathin Flexible Organic Electrochemical Transistors with Additive Integration for Bioelectronic Applications

Optical transparency is highly desirable in bioelectronic sensors because it enables multimodal optical assessment during electronic sensing. Ultrathin (90%) and high transconductance (≈1 mS) in low-voltage operations (<0.6 V). Further, electroencephalogram acquisition and nitrate ion sensing are demonstrated in addition to the compatibility of simultaneous assessments of optical blood flowmetry when the transparent OECTs are worn, owing to the transparency. These feasibility demonstrations show promise in contributing to human stress monitoring in bioelectronics