Body Temperature Changes

Abstract: In recent years, the development and research of flexible sensors have gradually deepened, and the performance of wearable, flexible devices for monitoring body temperature has also improved. For the human body, body temperature changes reflect much information about human health, and abnormal body temperature changes usually indicate poor health. Although body temperature is independent of the environment, the body surface temperature is easily affected by the surrounding environment, bringing challenges to body temperature monitoring equipment. To achieve real-time and sensitive detection of various parts temperature of the human body, researchers have developed many different types of high-sensitivity flexible temperature sensors, perfecting the function of electronic skin, and also proposed many practical applications. This article reviews the current research status of highly sensitive patterned flexible temperature sensors used to monitor body temperature changes. First, commonly used substrates and active materials for flexible temperature sensors have been summarized. Second, patterned fabricating methods and processes of flexible temperature sensors are introduced. Then, flexible temperature sensing performance are comprehensively discussed, including temperature measurement range, sensitivity, response time, temperature resolution. Finally, the application of flexible temperature sensors based on highly delicate patterning are demonstrated, and the future challenges of flexible temperature sensors have prospected.

Abstract: Core body temperature changes across the ovulatory menstrual cycle, such that it is 0.3°C to 0.7°C higher in the post-ovulatory luteal phase when progesterone is high compared with the pre-ovulatory follicular phase. This temperature difference, which is most evident during sleep or immediately upon waking before any activity, is used by women as a retrospective indicator of an ovulatory cycle. Here, we review both historical and current literature aimed at characterizing changes in core body temperature across the menstrual cycle, considering the assessment of the circadian rhythm of core body temperature and thermoregulatory responses to challenges, including heat and cold exposure, exercise, and fever. We discuss potential mechanisms for the thermogenic effect of progesterone and the temperature-lowering effect of estrogen, and discuss effects on body temperature of exogenous formulations of these hormones as contained in oral contraceptives. We review new wearable temperature sensors aimed at tracking daily temperature changes of women across multiple menstrual cycles and highlight the need for future research on the validity and reliability of these devices. Despite the change in core body temperature across the menstrual cycle being so well identified, there remain gaps in our current understanding, particularly about the underlying mechanisms and microcircuitry involved in the temperature changes.

Abstract: Ekblom, B. C. J. Greenleaf, J. E. Greenleaf and L. Hermansen, Temperature regulation during continuous and intermittent exercise in man. Acta physiol. scand. 1971. 81. 1–10. Body temperature changes and heat dissipation responses were studied in three well-trained men during moderately heavy (60 % of maximal aerobic power) continuous and intermittent exercise at the same average metabolic rate and heat production. The purpose was to determine if hypothetical “work factors” induced specifically by muscular activity influenced body temperature regulation. Compared with continuous work; a) the equilibrium level of rectal temperature (Tre) during intermittent work was elevated 0.35° C which accounted for 21 % of the total Tre increase from resting, and b) the decreased sweating of 32 g/(m2. hr) during intermittent work resulted in a decreased evaporative heat loss of 18.6 kcal/(m2. hr) that could account for the increased intermittent work Tre. These responses appear to be manifestations of reduced thermoregulatory efficiency due, perhaps, to non-linearity in the relationship of body temperature to total work rate or to non-linearity in the contribution of non-thermal inputs at work rates above 100 % of max. VO2. It is also possible that other factors play a part, such as the frequency and duration of the work and rest cycles, rate of limb movement, or circulatory factors related to postural changes.