Integrated micro power frequency breath detector

Abstract

Monitoring vital signs, which include breathing, is often used both in clinical practice and at home. The paper presents a novel low power system that can be used to control breathing frequency and detect apnea, which uses a condenser-type humidity sensor supplied with input bias current of an operational amplifier. The new configuration of the sensor, which compensates for the amplifier saturation state during the exhalation phase, increases breath detection effectiveness.The presented system is energy efficient, consumes approx. 50μA and operates over a wide range of supply voltages, 1.8÷18V DC. It enables to detect even very weak breathing. The concept of the integrated system has also been presented. This system can work directly with digital circuits without converting the electric signal. The presented system is characterized by a very simple construction and offers a new solution both in the field of sensor technology and for the use of operational amplifiers.