Spirometry Pressure Sensors

Z-Track Eliminates Zero Drift

Spirometry – Lung Function Testing

A spirometer is a vital tool used to diagnose and manage many different types of lung diseases.  Spirometry products require high performance differential pressure sensors to accurately diagnose a patient’s lung functions. Additionally, these handheld units must provide highly accurate readings regardless of how the unit is positioned when held. Additional measurements are typically required to ensure accurate results due to unstable sensor zero functionality.

Spirometry measures lung capacity and volume under various test conditions. Some of the most common measurements:

  • Forced Vital Capacity (FVC) – largest amount of air that you can blow out after taking your biggest breath
  • Forced Expiratory Volume (FEV1) – amount of air you can blow out in the first second of exhalation.
  • PEF (Peak Expiratory Flow), MVV (Maximum Voluntary Ventilation), TLC (Total Lung Capacity), and other measurements.

For example, the value of FVC together with FEV1 can help diagnose the type of lung disease present. 

A low FEV1 value indicates that there is a blockage in the air flow out of the lungs – a critical item to be monitored for COPD (chronic obstructive pulmonary disease). Spirometry is thought to be the most reliable way to test your lungs for COPD and asthma. Additionally, Spirometry testing determines the severity of the disease and is done to cross check the efficacy of a given lung treatment. 

SP Series Differential Pressure Sensors

Superior Sensor Technology has optimized the SP Series of differential pressure sensors for spirometry and FOT (forced oscillation technique). This product family addresses the performance requirements with a highly unique and differentiated offering: 

  • Improved auto-zero performance using the proprietary Z-TrackTM algorithm to maintain minimal zero point deviation – Virtually eliminating the impact of zero drift.
  • Positionally insensitive devices – Maintaining consistent and highly accurate handheld readings regardless of physical orientation of the spirometer.
  • Sensor accuracy, total error band and short-term zero stability are the best in class – ensuring consistently precise Spirometry measurements, yielding faster and more accurate patient diagnosis.
  • Warm-up time is essentially eliminated – Excellent choice for time critical applications.
  • Low power consumption – compatible with leading handheld requirements.
SP Series product matrix

SP Series – Differential Pressure Sensors with Z-Track

SP Series


  • Highly integrated dual sensors with ADC and DSP
  • Selectable pressure range from ±250 Pa to ±40 kPa
  • Z-Track virtually eliminates zero drift
  • Ultra low noise, 19 bit effective resolution
  • Very high accuracy ±0.1% of selected range
  • Long term stability ±0.1% of FSS in first year
  • Output update rate of 500Hz
  • Selectable bandwidth filter from 25Hz to 250Hz
  • Temperature compensated from 0°C to 50°C
  • Supply voltage compensation
  • Fully integrated compensation math
  • Standard I2C and SPI interfaces

Engineering Design Resources

3D Model & Configurator: SP 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)

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 SP Series

One device can support up to 4 different pressure ranges from 250 Pa to 40k Pa across the SP Series, 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!

SP160 Multi-Range 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 replacing up to 8 different sensors
  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 4x reduction in sensor inventory costs and product obsolescence
  7. Allows manufacturers to build fewer product variants, significantly lowering working capital requirements and inventory

To ensure the utmost accuracy in medical devices, the company has developed its proprietary Z-Track technology that virtually eliminates zero drift. Zero error reduction is critical in medical devices such as Spirometers, where an inaccurate reading can have life changing consequences.

Z-Track provides greater accuracy to devices such as spirometers, resulting in more effective diagnosis and better treatment plans. As you can see from the figure, Z-Track maintains minimal zero-point deviation with results that are consistent regardless of elapsed time. When combined with the Superior Sensor’s position insensitivity capability, the company’s pressure sensors provide the most accurate readings for all types of spirometry equipment including handheld and desktop units. Not only are you certain that the device has virtually eliminated all zero errors, but you can be sure of accurate readings regardless of how the spirometer is positioned or used.

Z-Track Graph

Benefits of Z-Track Technology include:

  1. Eliminate zero errors to ensure the most accurate spirometer readings in the industry
  2. Consistent performance regardless of elapsed time
  3. Extremely fast data transfer rate
  4. More effective medical diagnoses and treatment plans

Video Corner

SP Series Benefits Video