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COVID-19: Sensors for Medical Ventilators

Lisheng Gao, Ph.D., Analyst
April 15, 2020

We all know that COVID-19 has been declared by the World Health Organization as a global pandemic. As of April 9, 2020, more than 1,400,000 cases have been confirmed across the globe, with more than 90,000 deaths due to the virus. The virus can cause severe pneumonia that leads to extreme difficulty breathing, requiring medical ventilators to facilitate respiration. Along with the dramatically increasing number of patients and demand for more medical ventilators, we are expecting a spike in demand for several critical sensors of medical ventilators in the near future.


Essential sensors with high demand

Airflow sensors monitor the airflow rate during the inspiratory and expiratory process. The sensors' readings inform the volume of air delivered to the patients by the machines. This is an essential parameter, as different patients have different requirements for gas flow rates and volumes.

For medical purposes, hot-wire anemometers are a top choices of flow sensor for medical ventilators. The core sensing materials are fine metal wires (usually made of platinum or Rhodium) that are electrically heated to above ambient temperatures. They measure the resistance changes of wires caused by gas flow-induced temperature changes. Compared to other gas flow sensing technologies, hot-wire gas sensors have higher sensitivity, higher frequency responses, and finer spatial resolutions. The sensors are suitable for medical ventilators, where high frequency variations and high velocity fluctuations of gas flows are normal. They are used for three crucial flow sensing cases in a ventilator system:

  • Inspiratory sensing – The sensors are designated to monitor the inspiratory airflow rate and send data to the central computers. They help enable instant fan control, thus ensuring that the tidal deliveries match the users' settings.

  • Expiratory sensing – The sensors measure patients' exhaling behaviors. They monitor and alarm on low minute ventilation and apnea. As a result, the sensors also perform safety checks to continuously monitor whether the system delivers the appropriate volume of gas to patients.

  • Proximal flow sensing – Unlike the two sensors above, which have delays due to their remote locations with respect to patients, proximal sensors are installed very close to the patients to enable quick response to respiratory system-caused changes in gas flows. Their primary function is to monitor the breathing behavior of patients and rapidly adjust the ventilators to synchronize between the devices and patients.

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Oxygen sensors monitor the oxygen concentration delivered to the patients. The sensors ensure that a sufficient amount of oxygen is given to patients to avoid hypoxemia. The most common types of sensors include galvanic sensors and polarographic sensors.

  • Galvanic sensors – The sensors are called oxygen cells. Oxygen diffuses upon the membrane and is reduced at the anode to create a voltage in the electrical circuit. The magnitude of the voltage is proportional to the concentration of oxygen. For prolonged treatment, the sensors need calibration due to measurement drift.

  • Polarographic sensors – The sensors let oxygen diffuse through the oxygen-selective membrane to participate in reactions that generate free OH, producing electrical currents. The magnitudes of the electrical currents are proportional to the oxygen concentration. Constant electric voltages need to be applied to the sensors during operation.

All these oxygen sensors suffer from limited life spans. The reactions need reagents, which are depleted during operation, thus requiring routine sensor replacement. 

The table below includes some essential information about the sensors:

COVID19 Sensors

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There is no immediate innovation that can be done on incumbent sensing technologies quickly. However, innovation can be done to fulfill some unmet needs for using and managing these sensors. Tracking the sensors can be challenging in a stressful work environment where unexpected interruptions are routine. Using digital tools can help medical providers ease the tracking work. For example, using radio frequency identification (RFID) to monitor the state of the sensors and send the information to central computers can help medical providers obtain the real-time data of the sensors, thus enabling real-time tracking features.

With the increased demand for ventilators, it is necessary to recognize that the sufficiency and redundancy of the consumable sensors used in these apparatuses are critical to the health and lives of patients. Companies manufacturing the sensors should be aware of the high demand for the sensors due to the COVID-19 crisis. 

In the meantime, companies should also consider adding digital tools to the sensors to help medical providers ease management work. Companies starting to manufacture ventilators should consider offering separate digital tracking tools that are compatible with RFID-enabled sensors and including extra sensors to facilitate the jobs in hospitals.

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Companies should expect the demand for these sensors to remain high for the rest of the year. With the increasing cases in India, South America, and Africa, in the coming months, the high demand may shift from Europe and North America to these regions.




- Additional COVID-19 Resources

- Blog: How to Prepare Innovation Teams for a Coronavirus Driven Downturn

- Blog: Can Innovation Stop a Global Pandemic?

- Executive Summary: The Digital Transformation of Healthcare

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