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Mechanical Ventilators

Pressure Sensors in Medical Applications

Pressure sensors are pressure sensing devices, that can be applied in a wide variety of applications. Their measurement principle is based on the piezoelectric effect that transforms a pressure signal into an electric signal. Since pressure is also correlated with the flow rate in the mechanics of liquid and gaseous media, pressure sensors are indispensable components in flow measurement systems that enable reliable and accurate flow-rate control. The measured pressure range of our pressure sensors is a few millibars to a few bars. Pressure sensors can therefore be used as flow switches, that monitor the flow rate and notify a measuring device or a system that a predefined flow threshold has been reached. That is especially important in life-saving medical applications where accuracy is essential. Pressure sensors can form, for example, part of medical ventilators, dialysis systems, infusion pumps, to name just a few. In this document, we focus on the function that pressure sensors have in mechanical ventilators.

What is a Mechanical Ventilator?

A mechanical ventilator is a typical example of invasive ventilation since a tube is
inserted through the mouth into the trachea (windpipe) to prevent the patient’s lungs
from collapsing and assist the breathing function. Depending on the selected mode
of operation, the ventilator should be able to deliver inspiratory air with the required
pressure, volume, or any predefined flow waveforms.

HYB Pressure Sensors

HYB 3000 series differential pressure sensors

How Does a Mechanical Ventilator Work?

A ventilator is a relatively complex system that consists of several valves and sensors along with a processing unit, designed to execute the required control algorithms. In general, it consists of three main sub-systems:

  • The “Inspiratory Flow Delivery System”, which is responsible for generating and manipulating the oxygen-enriched air that is sent into the patient’s lungs.
  • The “Expiratory Path”, which provides the appropriate path for exhalation.
  • The “Processing unit”, which controls the operation of the entire system, based on the
  • information obtained from various sensors and the parameters, specified by the clinician.

Based on the information, received from a differential pressure sensor, an example of its task could be: the sensor opens the “Inspiratory Valve” during inhalation and closes the “Expiratory Valve” and vice versa during the exhalation.

Positive-pressure ventilators these days prevail over negativepressure ventilators

Pressure Sensors in Mechanical Ventilators

Not all mechanical ventilators are the same, however, few common areas exist – e.g. functional and logical assemblies and modules – where pressure sensors are being used. Besides an absolute pressure which measures the ambient pressure and is usually located at the outer part of the ventilator, a low-pressure sensor is needed which feeds the measured air pressure in the mask/supply tube to a processing unit for measurement and regulation of the breath pressure.

For COVID-19 patients, a echanical ventilator is an indispensable medical device

Assortment of HYB Pressure Sensors in Medical Ventilators

At HYB company we provide the pressure sensors, suitable for medical ventilators, of the following types (see also the scheme above):

  • Gauge pressure sensors. These heavy-duty pressure sensors (or supply pressure transducers) are used for pressure measurement between a filter and a pressure regulator from the ambient air and oxygen inputs and must support pressure ranges between 2 bars (30 psi) and 7 bars (100 psi) of range.
  • Differential and bidirectional low-pressure sensors (or flow transducers). These are very precise, low-pressure sensors and are used to measure the airflow and to adjust the oxygen concentration. Sensors must cover pressure ranges between 10 mbars (0.1 psi) and 100 mbars (1.5 psi) of range.
  • Absolute/Barometric pressure sensors are used for monitoring ambient/atmospheric pressure. These are used to adjust the breathing air to barometric changes and changes of height in the batient’s environment and must cover the pressure ranges between 700 mbars (10 psi) and 1250 mbars (18 psi) of range.

The sensors, mentioned above, are used for pressure measurement:

  • on the inspiratory path (applied to the patient),
  • on the tubes of the gases leading to an external humidifier, and
  • on the expiratory path (from the patient when breathing into the ventilator).

Tradition, knowledge and flexibility enable customized solutions

HYB digital 3000 series, in action

Pressure Sensor Series Recommendation

At HYB company we have experienced the biggest market success with our HYB 3000series, HYB 4000 series, and HYB 8000 series of pressure sensors. Our niche position on the market of pressure sensors is based on vast knowledge and experience gained through almost half a century of pressure sensors production (the company was founded back in 1972) and the flexibility of a relatively small company, capable of quick adaptation to specific customer’s requirements. Our pressure sensors are also capable of air temperature adaptation, which enables higher patient comfort.

Features of Pressure Sensors Series

Features of each pressure sensors series can be found in the Data Sheets of each sensor type. If you have some questions or special requests, don’t hesitate to contact our customer support at: inquiry@hyb.si and we will be glad to customize our equipment to your system or device.

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