Determination of heart rate using a high-resolution temperature measurement

A high resolution temperature measurement system able to measure temperature fluctuations down to 0.1 mdegC was developed. It was based on thermistors, which were fed with an ac signal to ensure a good signal-to-noise ratio (SNR). Two different configurations were tested, one unipolar and the other differential. The final system was inexpensive, easily portable and performed a noninvasive determination of temperature. It measured either volume or surface temperatures. A good SNR for both configurations using different types of thermistors was achieved. To evaluate a practical application of this system, temperature fluctuations were measured on the skin, in the proximity of different arteries, from where the heart rate was determined. The system may have many potential applications, in fields ranging from biomedicine to aerospace engineering