Temperature measurement and control system for transtibial prostheses: Functional evaluation.

The accumulation of heat inside the prosthetic socket increases skin temperature and fosters perspiration, which consequently leads to high tissue stress, friction blister, discomfort, unpleasant odor, and decreased prosthesis suspension and use. In the present study, the prototype of a temperature measurement and control (TM&C) system was designed, fabricated, and functionally evaluated in a phantom model of the transtibial prosthetic socket. The TM&C system was comprised of 12 thermistors divided equally into two groups that arranged internal and external to a prosthetic silicone liner. Its control system was programmed to select the required heating or cooling function of a thermal pump to provide thermal equilibrium based on the amount of temperature difference from a defined set temperature, or the amount of difference between the mean temperature recorded by inside and outside thermistors. A thin layer of aluminum was used for thermal conduction between the thermal pump and different sites around the silicone liner. The results showed functionality of the TM&C system for thermoregulation inside the prosthetic socket. However, enhancing the structure of this TM&C system, increasing its thermal power, and decreasing its weight and cost are main priorities before further development.

A novel instrument for logging nearwork distance.

PURPOSE: To validate a novel ultrasonic sensor for logging reading distances. In addition, this device was used to compare the habitual reading distances between low and high myopes. METHODS: First, the stability and sensitivity of the ultrasonic device were determined by repeated measures using artificial targets. Then, thirty Hong Kong Chinese (20-30 years) were recruited, of whom fifteen were considered to be high myopes (mean ± S.D. = -8.7 ± 0.5 D) and 15 to be low to non-myopes (mean ± S.D. = -2.0 ± 0.2 D). Each subject read a newspaper with their habitual visual aid continuously for 10 min in two sessions at their preferred working distance(s). The reading distances were recorded continuously using a novel nearwork analyzer. The modal working distance was considered as the 'habitual' reading distance. In addition, habitual reading distance was reported orally by each subject. RESULTS: The nearwork analyzer gave accurate and repeatable measurements over a range of distances and angles. Using this instrument, high myopes were found to have a significantly shorter reading distance than low myopes or non-myopes (mean ± S.D. = 35.9 ± 9.8 cm vs 50.9 ± 24.8 cm; two-sample t-test, p = 0.04, df = 18). The reading distances reported orally by the subjects were not correlated with those recorded by the nearwork analyzer. CONCLUSIONS: The nearwork analyzer was found to be an effective tool for measuring nearwork reading distance in a small group of emmetropic and myopic adults over a 10 min interval. Differences between the reading distance between high myopes and low/non-myopes was detected by the device. Further study is needed to determine if a closer working distance is a cause or effect of myopia development.