Design and analysis of electrically calibrated tympanic thermometers.

A new tympanic thermometer is analyzed and testedexperimentally. An electrically calibrated pyroelectric detector ofspecial configuration is employed to determine a person's bodytemperature. An energy-storage, power-supply-isolated capacitor isused as the electrical heating reference. The new thermometerdesign has an accuracy within ?0.1 degrees C with a 90% confidence and isimmune to ambient temperature, detector aging, and parametervariations. An equivalent-circuit model is established in theanalysis to account for the heat exchanges among the tympanum, thesurroundings, and the detector as well as for the electrothermalbehavior of the detector. The model provides effective simulationof the thermometer with PSPICE. Critical parameters governing theaccuracy and the limitation of the tympanic thermometer are alsopointed out by the simulation.