Thermistor For Body Temperature Measurement

Avoid dewing and condensation unless thermistor is specified for these conditions.

Thermistor for body temperature measurement.

Temple and forehead type thermometers use the same technology to measure infrared radiation as ear type thermometers they just measure it from a different location on the body. Perfluoropolyethers such as galden. However ptc thermistors have a sort of tipping point and greatly change the resistance at some temperature. Te connectivity te manufactures ntc negative thermal coefficient thermistors thermopiles and digital temperature sensors to support the wide range of accuracy packaging and performance conditions amongst the different.

The thermistor measures the cold junction temperature of the thermopile and both the thermopile and thermistor measurements are used to calculate the body temperature. Since the human skin acts as a thermal insulator the temperature of the skin isn t an accurate representation of actual body temperature. This makes the ptc thermistor a little harder to interface with. Temperature the component must not be immersed in water but in suitable liquids e g.

Measurement purposes checking the specified resistance vs. It could be used for human body temperatures but it depends on how you want to measure the body temperature. The silicone oil provides a very uniform temperature so many devices can be calibrated in a single cycle. The variable t is the ambient temperature in kelvin t0 is usually room temperature also in kelvin 25 c 298 15k b is the beta constant r is the thermistor resistance at the ambient temperature same as rt above and r0 is the thermistor resistance at temperature t0.

For this reason for most low cost temperature measurement ntc thermistors are preferred. Convert the temperature values to kelvins and invert. Thermistor linearization curves. The typical operating temperature range of a thermistor is 55 c to 150 c though some glass body thermistors have a maximal operating temperature of 300 c.

This temperature range is centered around the typical human body temperature of 38 c making the adt7422 ideal for accurate vital signs monitoring. It is relatively easy to calibrate your own response curves if you have an accurate temperature measurement standard. The temperature measurement of the surface of the body can be accomplished using different sensor technologies. Take the corresponding measured resistance values and compute the natural logarithm.

The adt7422 has an accuracy of 0 1 c over a temperature range of 25 c to 50 c. Types of sensors like ntc negative thermal coefficient thermistors thermopiles and digital temperature sensors.