Body Temperature Recorder
Body temperature is routinely monitored in clinical settings with infrared
ear thermometers which measure the infrared energy emitted from the
patient,s eardrum in a calibrated length of time. A short tube with a
protective sleeve is inserted into the ear, and a shutter is opened to
allow radiation from the tympanic membrane to fall on an infrared
detector for a period which is typically from 0.1 to 0.3 seconds in the
varieties surveyed. The device beeps when data collection is completed
and a readout of temperature is produced on a liquid crystal display.
This
kind of temperature from the eardrum has been found to be a clinically
reliable indicator of body core temperature. The eardrum is located
close to the hypothalmus, which is the body temperature regulator. The
membrane itself is thin and almost transparent in the visible, so you
would presume that it reliably tracks the temperature inside the
membrane so that the infrared energy it emits gives a good indication of
the inside temperature.
The
infrared energy falls on a thin pyroelectric crystal which develops a
charge proportional to that collected energy. Discharging the crystal
sends a current pulse through filters and conversion circuits which
compare the signal to tabulated data on temperature and calculate a body
temperature for the display.
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