Infrared thermography applied to the study of the thermal behavior of wheelchair cushion

A Single Subject, Feasibility Study of Using a Non-Contact Measurement to "Visualize" Temperature at Body-Seat Interface

Measuring temperature changes at the body-seat interface has been drawing increased attention from both industrial and scientific fields, due to the increasingly sedentary nature from daily leisure activity to routine work. Although contact measurement is considered the gold standard, it can affect the local micro-environment and the perception of sitting comfort. A non-contact temperature measurement system was developed to determine the interface temperature using data gathered unobtrusively and continuously from an infrared sensor (IRs). System performance was evaluated regarding linearity, hysteresis, reliability and accuracy. Then a healthy participant sat for an hour on low/intermediate density foams with thickness varying from 0.5−8 cm while body-seat interface temperature was measured simultaneously using a temperature sensor (contact) and an IRs (non-contact). IRs data were filtered with empirical mode decomposition and fractal scaling indices before a data-driven artificial neural network was utilized to estimate the contact surface temperature. A strong correlation existed between non-contact and contact temperature measurement (ρ > 0.85) and the estimation results showed a low root mean square error (RMSE) (<0.07 for low density foam and <0.16 for intermediate density foam) and high Nash-Sutcliff efficiency (NSE) values (≈1 for both types of foam materials).

Review of Measuring Microenvironmental Changes at the Body-Seat Interface and the Relationship between Object Measurement and Subjective Evaluation

Being seated has increasingly pervaded both working and leisure lifestyles, with development of more comfortable seating surfaces dependent on feedback from subjective questionnaires and design aesthetics. As a consequence, research has become focused on how to objectively resolve factors that might underpin comfort and discomfort. This review summarizes objective methods of measuring the microenvironmental changes at the body–seat interface and examines the relationship between objective measurement and subjective sensation. From the perspective of physical parameters, pressure detection accounted for nearly two thirds (37/54) of the publications, followed by microclimatic information (temperature and relative humidity: 18/54): it is to be noted that one article included both microclimate and pressure measurements and was placed into both categories. In fact, accumulated temperature and relative humidity at the body–seat interface have similarly negative effects on prolonged sitting to that of unrelieved pressure. Another interesting finding was the correlation between objective measurement and subjective evaluation; however, the validity of this may be called into question because of the differences in experiment design between studies.

Microclimate evaluation of strap-based wheelchair seating systems for persons with spinal cord injury: A pilot study

STUDY PURPOSE

The purpose of this pilot study was to assess microclimate characteristics of two versions of a strap-based wheelchair seating system (perforated and solid straps) and to conduct preliminary microclimate comparisons of subjects' current wheelchair seating systems.

MATERIALS AND METHODS

In this pilot study, the microclimate properties of two variations (solid and perforated) of a strap-based seating system were compared with two commonly used seating systems. Six subjects sat on three different seating systems each for 100-min test periods, while temperature and relative humidity were measured with a single sensor adjacent to the skin-seat interface. Additionally, thermal images of the seat interface were collected before and after each test period.

RESULTS

The thermal images revealed that the maximum surface temperature of the solid-strap-based seating system was significantly lower than the other seating systems, -1.21 °C. (95% CI -2.11 to -0.30, p = 0.02), immediately following transfer out of the seat. Five minutes after transferring out of the seat, the perforated-strap seat was significantly cooler than the other seats -0.94 °C. (95% CI -1.59 to -0.30), p = 0.01, as was the solid-strap-based seat, -1.66 °C. (95% CI -2.69 to -0.63), p = 0.01. There were no significant differences in interface temperature or relative humidity measured with the single sensor near the skin-seat interface.

CONCLUSION

This pilot study offers preliminary evidence regarding the microclimate of the strap-based seating systems compared with other common seating systems. Clinically, the strap-based seating system may offer another option for those who struggle with microclimate management.