How Does an Electric Thermometer Work

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.

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