High resolution temperature measurement

We have developed a high resolution temperature measurement system, able to measure down to 0.1 m/spl deg/C, which is inexpensive and easily portable. We propose a measurement based on thermistors fed with an AC signal to give a better signal to noise ratio and compare two different configurations: absolute and differential measurements. It works either in a volumetric or surface environment, for non-invasive temperature determination. As an application, we have measure temperature fluctuations in the body skin, on different arteries, and we have extracted the heart rate from the recorded temperature pattern. We have achieved a good signal to noise ratio in both configurations and using different types of thermistors. A wide range of application possibilities, from biomedical to aerospatial measurements, are possible with this system.