Michal Martinka

Thermo-physiological comfort of automotive seating is governed by the complex interaction between seat-cover materials, their structural configuration, and the heat and moisture exchange occurring at the seat–body interface during prolonged sitting. While numerous studies have examined individual textile constructions or isolated comfort parameters, integrated evaluations combining objective material testing with dynamic microclimate measurements under realistic loading conditions remain limited. This study thoroughly examined six commercially important vehicle seat-cover materials that represent laminated, warp-knitted, and woven polyester architectures. Standardized laboratory techniques were used to quantify objective comfort qualities, such as air permeability, water vapor permeability, thermal resistance (Rct), and evaporative resistance (Ret) and transient heat flux test (H-test). Simultaneously, a multi-sensor system was used to constantly monitor temperature and relative humidity at the seat–body interface during sitting loading in a controlled subjective microclimate experiment at room temperature. The findings show that lamination technique and textile structure have a major impact on both transient microclimate behavior and steady-state material properties. Increased air and moisture transmission in warp-knitted and more open structures resulted in reduced evaporative resistance and more stable microclimate conditions. Denser laminated structures, on the other hand, exhibited more resistance to heat and evaporation, which led to a greater buildup of moisture when they were seated. Different temporal responses in temperature and humidity were also shown by the multi-sensor microclimate studies, underscoring the significance of assessing comfort beyond static material metrics. This study demonstrates that static thermos-physiological parameters alone are not sufficient to predict real stated comfort behavior. By integrating time-resolved microclimate analysis under realistic seated loading with standardized testing, a more reliable evaluation framework for automotive seat-cover comfort is proposed.

This study developed a wearable fiber Bragg grating (FBG) sensor system and explored the measurement of respiratory rate during daily activities of life such as standing, walking, and running. The measurement system used was a wearable FBG interrogator that we developed ourselves. An FBG sensor, which is an optical fiber type strain sensor, was installed on the inner surface of the belt, and this belt was wrapped around the body. The respiratory cycle calculated from the respiratory strain signal measured by the FBG sensor was almost identical to the reference respiratory cycle measured by the temperature sensor. Initially, the pressure applied by the belt was found to cause discomfort over prolonged use. This issue was resolved by further re-fining the belt shape. Respiratory strain was almost accurately measured with the improved belt even when the following daily activities occurred: standing, walking at 4 km/h, and running at 10 km/h. Additionally, it provided a high S/N ratio respiratory strain signal even when participants were asked to walk in a hallway and up and down stairs. The sensor system developed in this study can help measure respiratory rate in daily life without interference.

This study aimed to identify the optimum installation position of an FBG sensor for accurate detection of radial artery pulsation strain. Six FBG sensors were installed in 2 rows and 3 columns at 5 mm intervals, and the average wavelength shift length due to pulsation strain was calculated from the six pulsation strain signal waveforms measured simultaneously and analyzed using a 3×5 matrix. Pulsation strain was detected with a downward or smaller upward strain signal as the measurement point was farther from the pulsation point. Larger strain was detected at the measurement points away from the pulsation point in the arterial or axial directions of the optical fiber than in the oblique direction. At measurement points farther from the pulsation point in the direction of the radial artery, the pulsation strain signal was greater than at measurement points farther in the axial direction of the optical fiber. The pulsation strain signals were measured at a wavelength shift of approximately 50% of the signal measured at the pulsation point at measurement points ±5 mm away in the direction of the radial artery. Therefore, the optimal measurement point of the FBG sensor was found to be within ±5 mm in the arterial direction, including the pulsation point. The results of this study will contribute to the development of textile products (smart textiles) that can measure biological information using FBG sensors.