CPAP Pressure Sensors

Dual Sensor Solution for CPAP, BiPAP and APAP Applications

CP Series Product Matrix

CP Series – Highly Integrated Dual-Sensor Solution

Summary of Benefits in under 90 seconds

Engineering Design Resources

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Superior Technology for Sleep Apnea &

Other Respiratory Applications

Positive Airway Pressure

Positive airway pressure (PAP) treatment uses a machine to pump air under pressure into the airway of the lungs. This helps keep the windpipe open during sleep. There are three common types of PAP machines:

  1. CPAP (continuous positive airway pressure) delivers a continuous level of air pressure,
  2. BiPAP (bi-level position airway pressure) delivers different air pressures for inhalation and exhalation,
  3. APAP (automatic positive airway pressure) delivers different pressure rates throughout your sleep, based on how you inhale.

There are many applications where PAP devices are used, including:

  • Sleep Apnea
  • COPD (chronic obstructive pulmonary disorder)
  • Pre-term infants whose lungs are not fully developed
  • Respiratory failure (home ventilation devices)
  • Asthma
  • Pneumonia
  • OHS (obesity hypoventilation syndrome)
  • Pulmonary edema

Technology Optimizations for PAP

Superior Sensor Technology has optimized the NimbleSense architecture for PAP applications with the CP Series of highly integrated dual sensor devices. This product family addresses the performance requirements of this market with a highly unique and differentiated offering:

  • Fully integrated dual sensor sub-system that simplifies product design and reduces overall system cost.
  • Highest levels of accuracy and performance due to the architecture’s extremely low noise floor.
  • Highly flexible and customizable solution as both sensors support multiple pressure ranges and module has a selectable bandwidth filter.
  • Very fast 2 msec response time.
  • Optional fan control further simplifies design and increases overall system performance:
Diagram of a sleep apnea machine implementation

Recommended NimbleSense Features for CPAP/BiPAP/APAP

  • Multi-Range
  • Closed Loop Control
  • Advanced Digital Filtering
Multi-Range

Each CP device has two pressure sensors and both can support up to 4 different pressure ranges. Each pressure range is factory calibrated and optimized to ensure no degradation in a 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 Sensor 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!

CPAP/BiPAP/APAP Multi-Range Sensor Comparison

Benefits of Multi-Range Technology include:

  1. Design flexibility with ability to ‘tweak’ pressure range throughout development cycle
  2. Simplified product design with one sensor fulfilling all your product needs
  3. Ability to quickly develop product variants at different pressure ranges without changing hardware design
  4. Greater economies of scale by purchasing larger quantities of the same product
  5. Reduced manufacturing complexity and costs due to simplified calibration of sensors
  6. Up to 8x reduction in sensor inventory costs and product obsolescence
  7. Allows manufacturers to build fewer product variants, significantly lowering working capital requirements and inventory
Closed Loop Control

Closed Loop Control adds capabilities to set and maintain flow rates via pressure management by directly controlling fans, motors, valves and actuators. Superior Sensors offers the option to have this capability integrated into the sensor in order to more effectively set and maintain flow rates by directly controlling these elements to maintain flow rate targets.

Basic Closed Loop Control System

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 Sensor 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 and used in combination with the company’s proprietary noise filtering, resulted in greater than 100x reduction in loop delay.

Closed Loop Control Air Quality Block Diagram

Benefits of the integrated Closed Loop Control include:

  1. Greatly reduce loop delays to improve accuracy and responsiveness of your product
  2. Improve the reliability of your product by eliminating discrete parts
  3. Reduce overall system costs
  4. Minimize system power and heat
  5. Simplify product design
  6. Speed time to market
Advanced Digital Filtering

Superior Sensor’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.

Advanced Digital Filter - Transfer Function
Advanced Digital Filter - Processing Example

Benefits of the advanced digital filtering technology include:

  1. Greatly reduce 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.
  2. Eliminate noise sources such as fans and blowers before they reach the pressure sensing sub-system.
  3. Simplify product design with an integrated approach.
  4. Speed time to market by not having to design an external filtering system.

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