Ricerc@Sapienza

A possible way of managing critical chronic disease is continuous monitoring of the health of the patient. One of the major growing diseases around the world is Cardiovascular diseases (CVDs). An Electrocardiogram (ECG), the electrical activity of the heart, is believed to be a very effective way of detecting heart-related problems noninvasively using conductive electrodes. Recent progress in wearable healthcare technology has made it possible for doctors to remotely observe the health conditions of their patients. However, conventional gel Ag/AgCl electrodes suffer from several drawbacks to be used in wearable devices due to their limited shelf life and allergic reaction to the skin. However, wearable dry electrodes resolve these problems and allow long-term continuous measurements regardless of patients¿ locations and status (e.g.: sleep or exercise). It is reasonable to hypothesize that the patient will sweat during the use of such electrodes and therefore, the sweat effect on skin-electrode impedance has to be assessed to avoid possible errors during, for instance, ECG measurement. A new and more accurate impedances measurement method will be investigated in this work, as opposed to the conventional way of impedance measurement by current probing. This method will be based on connecting known resistors in parallel to the inputs of a low noise pre-amplifier in a way that the interfacing of resistors will be controlled with the help of switches. A microcontroller will control the state of the switches and compute the root-mean-square (RMS) of the output voltage at different positions of the switches. This method will assess the variation of the skin-electrode impedance in the presence of sweat and identify the validity of the acquired biopotential signal.