2-12. HOW DOES AN ELECTRIC THERMOMETER WORK?
An electric thermometer may be battery-powered or plug into an electric outlet.
The operating instructions will vary from one model to another. Therefore, you must be
familiar with the operating instructions for the thermometer that you will be using. Pay
special attention to the "warm up" requirements.
a. Probe. The electric thermometer uses a metallic sensing device called the
probe. The probe is like the mercury in a glass thermometer in that the probe absorbs
heat from the body tissue that surrounds it. An electric thermometer usually has two
probes. The probe that is color-coded blue is used to take oral temperatures. The
probe that is color-coded red is used to take rectal temperatures. Both probes are
usually the same shape and size.
b. Probe Cover. Just as the mercury in a glass thermometer never actually
touches the patient, a probe is kept from touching the patient's body by a probe cover.
The cover is usually made of paper and is discarded after one use. The probe cover
gives the electric thermometer a great advantage over glass thermometers in that the
electric thermometer is ready to be used again once that the used cover is disposed of
and replaced by a new probe cover. A glass thermometer, on the other hand, must be
cleaned and sterilized before being used again.
c. Display. The probe has a cord that plugs into the main body of the electric
thermometer. The thermometer body displays the information obtained from the probe.
An electric thermometer may have either a digital or a scale display.
(1) Digital display. If the electrical thermometer has a digital display,
numerals showing the patient's temperature will be shown on the screen. The electric
thermometer in figure 2-3 has a digital display.
Figure 2-3. An electric thermometer.