Wearable Chipless Sensor for Breath Rate monitoring

Respiratory rate is one of the most important vital signs for complete monitoring of the health condition of individuals and early detection and diagnosis of illnesses related to the respiratory system. In this work, a novel sensor for breath rate monitoring is presented. The proposed sensor relies on the movement of the body during respiration for the estimation of the respiratory rate. The sensor is composed of two main components; spiral resonator (SR) tag that is realized on by means of ink-jet printing of conductive ink on a flexible substrate, and a microstrip probing loop. The tag is integrated in the innermost garment worn by the individual and located on the abdomen at the level of the umbilicus. The sensing principle is based on the variation of the measured input impedance with the distance between the interrogating probing loop, that acts as the antenna of the reader, and the SR tag. The design of the proposed sensor presented and verified using experimental measurements. The proposed sensor is characterized by its simple design, single-operating frequency, and high accuracy.