Ventilator Pressure Sensors
Extreme Resolution and Oversampling Improve Synchrony
Ventilators Require the Highest Reliability
Medical ventilators are sophisticated mechanical ventilation systems designed to move breathable air into and out of the lungs for patients physically unable to breathe on their own. Today’s systems are electronically controlled through embedded processing to tightly manage air pressure and flow characteristics to meet individual patient requirements. These systems are considered life critical as system failures may result in serious harm to the patient. As such, these mechanical ventilators are carefully designed to ensure single points of failure do not harm patients.
The Ventilator industry manufactures the industry’s highest reliability products with appropriate features offered at acceptable cost levels. Identifying and replacing sensors prior to failure increases system reliability and has been shown to lower system alarm rates. This in turn, saves lives.
VN Series Family of Pressure Sensors
The VN Series is a comprehensive set of pressure sensors for ventilator and high flow oxygen devices. The family of products includes sensors for measuring inlet (wall and tank), flow, inspiratory, expiratory and barometric pressures. The series utilizes Multi-RangeTM technology to create the industry’s widest dynamic range, eliminating the need for fine tuning or additional calibration.
- Eliminates need for the ventilator to oversample sensor outputs, as the sensor oversamples at 12kHz and includes internal bandwidth filters to provide a clean > 1kHz data rate.
- Highest levels of accuracy and performance due to the architecture’s extremely low noise floor.
- Pure O2 compatible.
- With optional advanced digital filtering customization and a 3-mode pressure switch, the VN Series is more than a pressure sensor – it is a pressure sensing sub-system.
New Extreme Resolution Sensors
With the introduction of the VN Series, Superior Sensor Technology is taking resolution to the extreme! The product family has 24-bit output resolution, and we offer two extreme resolution sensors with approximately 18-bit effective resolution at high bandwidth. This is significantly higher than any other pressure sensors, and in critical high speed applications like ventilators, the difference is significant.
The chart below shows the actual measured effective resolution of both VN extreme and standard resolution parts compared to several high-volume parts from competing companies. Not only do the VN parts support a wider bandwidth, but the gap in effective resolution continues to grow the higher the bandwidth (speed) requirement of the application.
As seen in the graph, at 200 Hz bandwidth the extreme resolution VN sensors have a 16x lower noise floor versus the best performing competitive parts! At 500 Hz the gap in noise floor grows to at least a factor of 17! In addition, none of the competing parts have as wide a dynamic range as the VN Series sensors.
VN Series – Advanced Pressure Sensors for Ventilators
Family of Sensors for Ventilators and High Flow Oxygen Devices
Devices with two checks are better suited for that application versus those with one check
For an example of how the VN Series can be implemented in a mechanical ventilator, download the Ventilator Diagram.
For an example of how the VN Series can be implemented in a high flow oxygen therapy, download the High Flow Diagram.
- Inspiratory, expiratory, flow, inlet & barometric pressure sensors
- Highly integrated sensor with ADC and DSP
- Output Data Rate up to 1.09kHz
- 24-bit resolution (each selected range)
- Pure O2 compatible
- Up to 8 Selectable Pressure Ranges per Device
- Exceptional Zero Stability
- Selectable Bandwidth Filter from 1.0Hz to 500Hz
- Total Error Band less than 0.15% FSS
- Very High Accuracy ±0.05% of Selected Range
- Long Term Stability ±0.10% FSS
- Sensors for flow available in high and extreme resolution
- Inlet & Barometric sensors include silicone gel protection
- Temperature Compensated 0°C to 50°C
- Fully Integrated Compensation Math
- Standard I2C and SPI Interface
Engineering Design Resources
3D Model & Configurator: VN Series
Select product requirements from table to see the order part number. In addition, view & download 3D Model in native CAD format.
(model download requires registration at CADENAS PARTsolutions)
Getting Part Info…
90° Port Adapters
Depending on your product design, you may need the ports facing to the sides instead of the top. Superior offers highly reliable, high quality adapters that plug into the two ports of our pressure sensors for easy implementation. With these 90° adapters, there is no need to worry about z-height.
90° adapters are available with and without o-rings:
KP-RAR: without o-rings
KP-ROR: with o-rings
Adapters are offered in packages of 50 and 1000.
Recommended NimbleSense Features for VN Series
One device can support up to 8 different pressure ranges, and each pressure range is factory calibrated and optimized ensuring no degradation in total error band, accuracy or stability regardless of the range selected. This eliminates the complexity and headaches of working with multiple sensors.
Instead of having to research, purchase and design-in multiple parts, a single Multi-Range part simplifies both the design and manufacturing of a product. Designing in the same part throughout your designs is much more efficient than having to select multiple components. When you design in each of the Superior pressure sensors, the setting of the pressure is done via a single software command. It’s that simple. Add the fact that there is only one product to inventory, and your manufacturing team will also appreciate the value of Multi-Range!
Benefits of Multi-Range Technology include:
- Design flexibility with ability to ‘tweak’ pressure range throughout development cycle
- Simplified product design with one sensor replacing up to 8 different sensors
- Ability to quickly develop product variants at different pressure ranges without changing hardware design
- Greater economies of scale by purchasing larger quantities of the same product
- Reduced manufacturing complexity and costs due to simplified calibration of sensors
- Up to 8x reduction in sensor inventory costs and product obsolescence
- Allows manufacturers to build fewer product variants, significantly lowering working capital requirements and inventory
Closed Loop Control adds capabilities to set and maintain flow rates via pressure management by directly controlling motors, valves and actuators. Superior offers the option to have this capability integrated into the sensor in order to more effectively set and maintain flow rates by directly controlling motors, valves and actuators to maintain flow rate targets.
The integrated Closed Loop Control design significantly reduces loop delays in the electronic circuit by up to 100x. This integrated solution also eliminates the need to design and implement a complex control loop system, resulting in more efficient, more reliable and less costly products. Closed Loop Control is of extreme value in medical respiratory devices such as ventilators and CPAP, as well as in air quality measurement products.
The figure below shows a block diagram of an implementation of the Superior Closed Loop Control for an air quality application. In order to effectively measure the air quality, we require maintaining a constant/known airflow through the viewing window. The differential pressure across the venturi directly measures the flow into this viewing window. The system sets a target pressure level across the venturi and the differential pressure sensor automatically increases or decreases the drive to the pump to maintain the targeted differential pressure, ensuring a constant airflow into the viewing window. This is accomplished with the NimbleSense closed loop circuit used in combination with the company’s proprietary noise filtering, resulting in greater than 100x reduction in loop delay.
Benefits of the integrated Closed Loop Control include:
- Greatly reduce loop delays to improve accuracy and responsiveness of your product
- Improve the reliability of your product by eliminating discrete parts
- Reduce your overall system costs
- Minimize system power and heat
- Simplify your product design
- Speed your time to market
Superior’s advanced digital filter is a multi-order filter that utilizes advanced filtering capabilities on the front-end of the sub-system to eliminate critical noise created by fans, blowers or other dry air/gas sources prior to reaching the pressure sensing sub-system. The NimbleSense advanced filtering capability removes sensor induced mechanical noise before it becomes an error signal that can adversely impact overall system performance. In customer deployments where our sensor replaced a competing component, we have seen greater than 10x reduction in sensor induced noise, thus greatly improving the SNR of the sensor output. In very low pressure systems, the improvement is even more significant.
Incorporating both standard and optional digital filters, this feature provides significantly better noise reduction and eliminates the need to design an external filtering system, resulting in more efficient, more reliable and less costly products. Our advanced digital filtering is optimized for each application to ensure mixed sampling noise is kept well below the noise floor. By removing the mechanical noise, we maximize overall system performance.
The example below is of a 4th order FIR filter customized to block pump noise above 50 Hz, which has noise of equal magnitude as the signal of interest. The lower graphs show the resulting impact of the advanced digital filtering.
Benefits of the advanced digital filtering technology include:
- Greatly reduced system noise levels by 10x or more, especially important in very low pressure applications. For noise prone systems, an improvement of 100x to 1000x is not unreasonable.
- Eliminate noise sources such as fans and blowers before they reach the pressure sensing sub-system.
- Simplify product design with an integrated approach.
- Speed time to market by not having to design an external filtering system.
A pressure switch is a mechanical or electronic device that is activated when a certain pressure threshold or set point is reached. These failsafe response components instruct the system to perform an action if a certain pressure threshold is met.
Types of Pressure Switches
Fixed Pressure Switches
As their name implies, fixed pressure switches have pre-set, non-changeable pressure thresholds that are set by the pressure switch manufacturer. The device maker receives the pressure switch already configured and cannot change values. Examples where fixed pressure switches are common are certain types of medical devices, such as ventilators.
Variable Pressure Switches
With variable pressure switches, the threshold value can be set either by the device maker or dynamically in the field. If it is controlled by the device maker, when they build their product they select certain resistor pairs that control the voltage input that determines the threshold. Once they build the product, the threshold value cannot be changed.
In cases where the threshold can be set in the field, this is typically done via software or a mechanical knob/switch. In this scenario, the pressure switch is usually not implemented as a safety feature. A good example is with air filters – where depending on the system implementation, the threshold value needs to be adjusted to account for any head loss in the flow stream.
Superior’s pressure switch changes state depending on the measured pressure being above or below a certain threshold. This can be used as a fast response failsafe feature for overpressure conditions, and to provide other simplified on/off system feedback. However, unlike other more common pressure switches, the Superior Sensor pressure switch includes three modes for setting threshold pressure, one fixed and two variable:
- Fixed mode: Superior Sensor Technology sets the threshold and provides the ‘ready for use’ configured sensor (with integrated pressure switch) to the device manufacturer.
- Variable mode 1: The device manufacturer can configure and set the proper thresholds at the time of product manufacturing.
- Variable mode 2: Pressure thresholds are field programmable via software, so the pressure switch can be ‘tuned’ after product manufacture depending on the use case.
Benefits of Superior’s integrated pressure switch include:
- Flexibility with 3 modes of operation
- Lower system cost as need for an external pressure switch is eliminated
- Smaller overall PCB footprint
- Improve the reliability of your product by eliminating external components
- Minimize system power and heat
- Simplify your product design
- Speed your time to market
With such a high demand for ventilators, it is critical that they continue to work without interruption. Eliminating failures before they become system alarms is a must. Implemented in close collaboration with partners, Superior’s proprietary Self Aware technology offers a capability that ensures maximum uptime and overall reliability.
Self Aware sensor technology tracks changes in error levels. By being part of a redundant system, the technology both eliminates a single point of failure service interruption and reduces false positives with respect to error notifications. Self Aware can reduce pressure sensor related alarm rates by up to 1000x.
If Self Aware technology is beneficial for your application, please contact us to discuss how we can implement this innovative feature to help differentiate your product.
VN Series Benefits Summary