A new scheme for reducing breathing trouble through MEMS based capacitive pressure sensor

Abstract

In this paper, a treatment of respiratory disorders with brushless DC motor (BLDC) driven positive airway pressure (PAP) respirator is developed. The proposed schema of the system consists of a BLDC motor driven blower fan aided by a MEMS capacitive type pressure sensor to measure respiration rate (RR). To measure the respiration rate, the array of such sensors are mounted below right nostril (RN) and left nostril (LN), in such a way that the nasal airflow during inspiration and expiration impinge on the sensor diaphragms directly. Due to irregularities in nasal airflow in some respiratory diseases, the RR varies from the normal rate (12---20). Thus, a supporting airflow regulatory system has been designed to reduce abnormalities in RR. The supporting system consists of a positive airway pressure (PAP) respirator with a blower fan to relieve patients breathing abnormalities. The MEMS based RR sensors help to monitor patients breathing rate continuously and finally maintain the required air pressure/flow by regulating the rpm of the blower fan through BLDC motor drive. In order to implement such a control action, we have chosen the sensorless drive of BLDC motor to construct a transportable as well as noise immune system. An algorithm has been developed to sustain normal RR for both bradypnea (RR 20), which puts into operation through ATmega 328 to facilitate high level precision controlled action. The control system alongwith the sensory part occupies limited space in few centimeters with light weight. As a result, the electronics of the whole system can be easily mounted at the outer surface of the tube connected with the nasal mask. The scheme of such a portable and cost effective system is described in this present work.