We used a fingertip PPG sensor and Lead I EKG to measure heart rate at both the fingertip and the chest. Blood pressure is estimated by tracking the interval between the peak of the R-wave in the EKG and the PPG, and relating it to arterial stiffness [1]. The system also uses an operational amplifier with a differential gain of 500 for the EKG.

Electrodes are attached to the person in 3 locations: above and below an eye, and behind the ear. Blinking is determined according to how the signal changes, and the amount of times this is done in a given range of time determines the rate. An operational amplifier and a programmable amplifier are used in this system to reduce noise and amplify the signal being collected.

The system has two conductive cords: one wrapped around the chest, the other around the diaphragm, and the average between the two will be used in the calculations. As the chest and diaphragm expand during inhalation, the cord gets stretched so the resistance increases. The number of breaths in a given range of time determines the rate.

A thermistor is positioned under the clothes in the axilla, as close to the core as possible. It is connected to a voltage divider circuit to track temperature change. As the temperature in the body rises, the resistance of the thermistor rises as well.