In positive airway pressure (PAP) therapy, a device pressurizes the lungs’ airways with air. This aids in maintaining an open windpipe while sleeping. Three varieties of PAP machines are commonly available:
- APAP (automatic positive airway pressure): Depending on breathing, automatic positive airway pressure, or APAP, will apply varying pressure levels while sleeping.
- CPAP (continuous positive airway pressure) maintains a constant air pressure level.
- BiPAP (bi-level positive airway pressure): For inhalation and expiration, different air pressures are delivered by BiPAP (bi-level positive airway pressure).
PAP devices are utilized in numerous applications, such as:
- Sleep Apnea
- Pulmonary edema
- Chronic obstructive pulmonary disease (COPD)
- Pneumonia
- Pre-term infants whose lungs are not fully developed
- Respiratory failure (home ventilation devices)
- Asthma
- Obesity hypoventilation syndrome (OHS)
CP Series Integrated Dual Pressure Sensor
Superior Sensor Technology has optimized the highly integrated dual-sensor devices in the CP Series for PAP applications. With the integration of a separate gage pressure sensor and differential pressure sensor into a single package, this product family offers a remarkably distinct and unique offering:
- Fully integrated dual sensor sub-system that lowers overall system costs and streamlines product design.
- Offered in dedicated 4-port and shared 3-port configurations for optimal design versatility.
- Maximum accuracy and performance because of the very low noise floor of the architecture.
- It is an extremely adaptable and adjustable solution because each sensor has a selectable bandwidth filter and supports different pressure ranges.
- Optional closed-loop control improves system performance overall and simplifies design even more.
Image Credit: Superior Sensor Technology
Source: Superior Sensor Technology
Image Credit: Superior Sensor Technology
CP Series – Highly Integrated Dual Sensor Solution
Family of sensors for CPAP, BiPAP, and APAP
Image Credit: Superior Sensor Technology
Source: Superior Sensor Technology
CP202 and CP302
Integrated Closed-Loop Control and Overpressure Indicator
The CP202/CP302 dual pressure sensors are an advanced development platform intended to characterize and productize closed-loop control-integrated CPAP sensors. Product development uses the programmable control parameters that are included in the sensors. In special sensors, these parameters are stored permanently.
Features (All CP Series products)
- Dual sensors that are highly integrated with ADC and DSP
- Combines gage and differential sensors into a single device.
- Each device has four differential ranges, ranging from ±250 Pa to ±2.5 kPa.
- Each device has four gage ranges: ±2 kPa to ±6 kPa.
- Provide voltage correction
- Adjustable bandwidth filter with a 25–250 Hz range
- Incredibly low noise, effective resolution of 17.5 bits
- Common SPI and I2C interfaces
- Exceptionally high precision ±0.05% of the chosen range
- Stability over the long run ±0.1% of FSS in the first year
- Accessible in configurations with three and four ports
- Update rate of output up to 500 Hz
- (Optional) advanced digital filtering
- Adjusted for temperature between 5 °C and 50 °C
- Completely integrated accounting for compensation
Engineering Design Resources
90° Port Adapters
Depending on how the product is designed, the ports may need to face the sides rather than the top. Superior provides incredibly dependable, premium adapters that easily fit into pressure sensors’ two ports. When using these 90° adapters, users do not need to worry about z-height.
90° adapters are available with and without o-rings:
- KP-ROR: with o-rings
- KP-RAR: without o-rings
Adapters are offered in packages of 50 and 1000.
Image Credit: Superior Sensor Technology
Recommended NimbleSense Features for CP Series
Multi-Range Technology
Image Credit: Superior Sensor Technology
The two pressure sensors on each CP device can detect up to four distinct pressure ranges. Each has been factory-calibrated and optimized to ensure stability, accuracy, and a constant total error band. This eliminates the intricacy and difficulties associated with using several sensors.
Using a Multi-Range part simplifies the design and manufacturing process by removing the need to find, buy, and integrate multiple parts.
Pressure adjustments are conveniently controlled with a single software command, and efficiency and ease of use are improved using the same component in all designs. Multi-Range offers manufacturing processes the convenience and added value of a single inventory item. To sum up, design and manufacturing teams recognize multi-range benefits.
Benefits of Multi-Range Technology Include:
- Lower manufacturing costs and complexity as a result of simpler sensor calibration.
- Adaptability in design allows for pressure range adjustments during the development cycle.
- Permits producers to create fewer product variations, greatly reducing the need for working capital and inventory.
- Streamlined product design by substituting one sensor for up to eight separate ones.
- The capacity to swiftly create product variations at various pressure levels without requiring modifications to the hardware design.
- Increased economies of scale through buying the same product in bigger quantities.
- Reduced inventory costs for sensors and product obsolescence by up to 8 times.
Closed Loop Control
Image Credit: Superior Sensor Technology
Through pressure management, closed-loop control improves the capacity to set and maintain flow rates by directly regulating motors, valves, and actuators. Superior offers the option to incorporate this functionality into the sensor, enabling more effective flow rate control and target maintenance.
Up to 100 times less loop delay occurs in electronic circuits, thanks to Superior's integrated closed-loop control design. Additionally, by removing the need to create a complicated external control loop system, this solution enables the production of more dependable, efficient, and reasonably priced goods. One cannot overestimate the advantages of an integrated closed-loop control, particularly in products for measuring air quality, HVAC systems, UAVs, and medical respiratory devices like CPAP.
The diagram shows a block layout showing the installation of an excellent closed-loop control system for an air quality application. Keeping the airflow through the viewing window constant and predetermined is crucial for accurate air quality measurement. The differential pressure across the venturi is a clear indicator of the flow entering the viewing window.
The differential pressure sensor automatically modifies the pump drive, up or down, to maintain the targeted differential pressure and an even airflow into the viewing window by setting a target pressure level across the venturi. Combining the company's unique noise filtering technology with the NimbleSense closed loop circuit allowed for a successful reduction of loop delay of over 100 times.
Image Credit: Superior Sensor Technology
Benefits of the Integrated Closed-Loop Control Include:
- Reduce loop delays significantly to increase the product’s accuracy and responsiveness.
- Eliminate discrete parts to increase the product's dependability.
- Cut down on the total cost of the system.
- Cut down on system heat and power.
- Reduce complexity in product design
- Expedite time to market
Advanced Digital Filtering
The state-of-the-art digital filter from Superior is a multi-order filter that uses sophisticated filtering techniques at the front end of the sub-system to eliminate critical noise before it reaches the pressure-sensing sub-system. Blowers, fans, and other dry air/gas sources cause this noise.
This is achieved by removing sensor-induced mechanical noise before it becomes an error signal that could impair system performance overall, using NimbleSense’s advanced filtering capability. By substituting a competing component in customer deployments, the sensor has produced a more than 10-fold reduction in sensor-induced noise, significantly increasing the SNR of the sensor output. This improvement is even more notable in systems operating at extremely low pressure.
This feature significantly improves noise reduction and eliminates the need to design an external filtering system, resulting in more effective, dependable, and affordable products. It does this by incorporating both standard and optional digital filters. Sophisticated digital filtering is adjusted to perfection for every application, guaranteeing that noise from mixed sampling is well below the noise floor. By eliminating mechanical noise, the system's overall performance is optimized.
Here is an illustration of a 4th-order FIR filter created especially to remove pump noise above 50 Hz or a noise level equal to the signal under observation. The graphs display the results of Superior's sophisticated digital filter.
Image Credit: Superior Sensor Technology
Benefits of the Advanced Digital Filtering Technology Include:
- Significantly decreased system noise levels - by a factor of ten or more - which is crucial in applications with extremely low pressure. An improvement of 100× to 1000× is not unusual for noisy systems.
- Before noise from fans and blowers reaches the pressure-sensing sub-system, eliminate their source.
- Make product design simpler by using an integrated strategy.
- Reduce time to market by avoiding the need to create an external filtering system's design.
Pressure Switch
When a predetermined pressure threshold or set point is reached, a mechanical or electronic device known as a pressure switch is triggered. These failsafe response parts give the system instructions on what to do if a predetermined pressure threshold is reached.
Types of Pressure Switches
Fixed Pressure Switches
As the name suggests, fixed pressure switches have pressure thresholds that the pressure switch manufacturer predetermined and cannot be changed. The pressure switch is delivered to the device manufacturer already configured. Fixed pressure switches are frequently found in various medical devices, including ventilators.
Variable Pressure Switches
The threshold value of variable pressure switches can be set dynamically in the field or by the device manufacturer. If the device manufacturer controls it, they choose specific resistor pairs that regulate the voltage input and establish the threshold during product construction. The threshold value cannot be altered after the product is built.
Threshold adjustments in the field are typically made using a mechanical knob, switch, or software. The pressure switch is typically not used as a safety measure in this situation. An excellent illustration of this is with air filters, where the threshold value must be changed based on the system implementation to consider any head loss in the flow stream.
Superior’s pressure switch changes state based on whether the measured pressure is above or below a specified threshold. This can give additional straightforward on/off system feedback and serve as a quick response failsafe feature for overpressure situations. The Superior Sensor pressure switch, in contrast to other, more widely used pressure switches, has three modes - one fixed and two variable - for determining the threshold pressure:
Fixed mode: Superior Sensor Technology establishes the threshold and gives the device manufacturer the configured, “ready for use” sensor (which includes an integrated pressure switch).
Variable mode 1: The device manufacturer can configure and set the appropriate thresholds at the time of product manufacturing.
Variable mode 2: Software allows for the field programming of pressure thresholds, allowing the pressure switch to be "tuned" based on the specific use case after the product is manufactured.
Benefits of Superior’s Integrated Pressure Switch include:
- Flexibility in three different operating modes
- Expedite time to market
- Reduced system costs because there is no longer a need for an external pressure switch
- Reduce complexity in product design
- Reduced total PCB footprint.
- Reduce the number of external components in the product to increase its dependability.
- Cut down on system heat and power.