We developed an e-textile bioelectrode composed of knit fabric coated with a conductive polymer and ionic liquid gel and evaluated its mechanical and electrical properties. We found that the electric resistance of the e-textile bioelectrode could withstand up to 30% stretching owing to the structural change in the knit fabric. We also found that the mechanical stress of the knit fabric with bioelectrode materials could be increased to 50 N at 100% stretch, while the stress of knit fabric was 10 N. This bioelectrode can also be used without any increase in electric resistance up to 30% stretch in a 1000-times cyclic test. The resultant mechanical and electrical properties can be used as a standard for e-textile bioelectrodes on knit fabrics.

In a previous study, a flexible thermal flow sensor for detecting respiratory airflow was installed inside the slip joint of an intubation tube system to support its insertion. In this study, the airflow stream distribution in the slip joint is systematically analyzed to determine the optimal placement of the airflow sensor. First, the airflow distribution in both the baby and adult tracheal intubation tubes was analyzed using finite element simulations. Backward flow was discovered near the inside surface of the slip joint during exhalation, with a stronger magnitude in the baby intubation tube in comparison with its adult counterpart. However, no backward flow was observed during inhalation. To clarify the simulated flow profile, the airflow stream inside the slip joint of the baby tracheal intubation tube during exhalation was examined experimentally. A stick-type airflow sensor was proposed and developed using MEMS technology for airflow measurements. The backward airflow was experimentally verified in the vicinity of the inside surface of the slip joint during exhalation, which was in agreement with the simulation results. Consequently, the airflow sensor is found to be optimal when placed around the radial center of the slip joint, which shows a consistent airflow profile under both inhalation and exhalation.

In this study, we successfully fabricated a minimum triaxial MEMS tactile sensor with a diameter of 320 µm for a medical catheter. The miniaturized sensor is expected to be installed onto the tip of the minimum guidewire to ensure a tactile sensor can be obtained to avoid an accident of breaking through blood vessel walls. After fabricating the detection unit and through-silicon via (TSV) unit, the two units were bonded using wafer-level gold-gold surface-activated bonding followed by clipping of the tactile sensor with a diameter of 320 µm. We confirmed that the proposed and optimized fabrication process realized an ultrasmall tactile sensor that can detect triaxial forces, which can be used in an advanced catheter system with a tactile-sensitive guidewire.

We propose a multilayered interconnection structure consisting of a textile, urethane film, and stretchable silver paste for tactile feedback. With this structure, we fabricated a prototype tactile-feedback device with an array of 10 vibration motors all wired under the same wiring resistance of 15 Ω within an area of 2.5×12 cm². This prototype device provides tactile feedback in a virtual reality system.