Heart rate and blood oxygen saturation level are essential medical parameters that can be measured optically by photoplethysmography. However, certain individuals present variability in skin absorption that can affect the proper quantification of both pulse and blood oxygen level. In this work, we designed an optical device capable of measuring these variables, trying to improve the accuracy by means of different electronic signal processing. A final accuracy of 0.5 beats per minute and 0.5% was determined for the heart rate and the oxygen saturation measurements, respectively. The sensor was used in one practical study with more than 100 participants where the resting heart rate and the pulse waveform were analyzed. Resting heart rate was shown to decrease with age and increase with BMI. Overall, the device performance makes it suitable to be used in the medical field and sports science.