When monitoring a person’s breathing the breathing activity, frequency, intensity and function of the organs involved are measured by pressure sensors. Relative, differential and absolute pressures sensors are used in the following devices:
- CPAP* apparatus
- Oxygen concentrators
Sleep apnea is a sleep disorder which affects millions of people. It is characterized by abnormal pauses in breathing or by periods of unusually shallow breathing during sleep. CPAP devices use a low, positive air pressure to keep airways open and enable regular breathing patterns.
Differential or bidirectional differential pressure sensors in a low pressure range of 50 to 100 mbar are used here.
*CPAP = continuous positive airway pressure
Respirators are life-saving devices for patients who cannot breath without supervision, for example when anaesthetized. They transport breathable air into and out of the lungs and are used in many places from intensive care units to devices for the home. Besides an absolute pressure sensor to measure the ambient pressure a low pressure sensor is needed which feeds the measured air pressure in the mask/supply tube to a microcontroller for measurement and regulation of the breath pressure. OEM sensors are therefore particularly suited to these applications:
AMSYS offers a range of differential and bidirectional low pressure sensors in the 40 to 100 mbar range.
Ambient pressure is measured by barometric pressure sensors (absolute pressure of 700 to 1,250 mbar). Measurements are taken to adjust the breathing air to barometric changes and changes in height in the patient’s environment.
Spirometers are non-invasive devices used to measure the volume flow of inhaled and exhaled air. Here, the lung volume is measured dynamically, enabling conclusions to be drawn on the function of the lungs.
One tried-and-tested way of measuring this is to use a bidirectional low pressure sensor with a range of 20 to 150 mbar which can directly measure the air volume in both directions.
Oxygen concentrators are used to concentrate oxygen from a gas reservoir (typically ambient air). Oxygen therapy can be performed using air enriched with O2. Patients with lung disease who require a higher oxygen concentration than that present in ambient air can also be treated with such devices.
Absolute pressure sensors with a range of 1 to 2 bar are used to measure increased oxygen concentrations.