Phase-change materials (PCM) can be used to reduce thermal stress and improve thermal comfort for workers wearing protective clothing. The aim of this study was to investigate the effect of PCM in protective clothing used in simulated work situations. We hypothesized that it would be possible to optimize cooling performance with a design that focuses on careful positioning of PCM, minimizing total insulation and facilitating moisture transport. Thermal stress and thermal comfort were estimated through measurement of body heat production, body temperatures, sweat production, relative humidity in clothing and subjective ratings of thermal comfort, thermal sensitivity and perception of wetness. Experiments were carried out using 2 types of PCM, the crystalline dehydrate of sodium sulphate and microcapsules in fabrics. The results of 1 field and 2 laboratory experimental series were conclusive in that reduced thermal stress and improved thermal comfort were related to the amount and distribution of PCM, reduced sweat production and adequate transport of moisture.

A laparoscopic surgeon sometimes experiences heat-related discomfort even though the temperature situation is moderate. The aim of this project was to design a cooling vest using a phase change material to increase thermal comfort for the surgeon. The project focused on the design process to reveal the most important parameters for the design of a cooling vest that could be demonstrated in a clinical setting. We performed an entire design process, from problem analysis, situation observations, concept for a prototype, temperature measurements, and a final design based on clinical testing. The project was conducted by a multidisciplinary team consisting of product designers, engineers, physiologists, and surgeons. We carried out four physiological demonstrations of one surgeon's skin temperatures and heart rate during different laparoscopic procedures. A commercially available cooling vest for firemen and two proof-of-concept prototypes were tested alongside a reference operation without cooling. To aid the final design, one person went through a climate chamber test with two different set-ups of cooling elements. The final design was found to improve the conditions of our test subject. It was found that whole trunk cooling was more effective than only upper trunk cooling. A final design was proposed based on the design process and the findings in the operating room and in the laboratory. Although the experiences using the vest seemed positive, further studies on several operators and more surgical procedures are needed to determine the true benefits for the operator.