Selection guide for Sensirion gas flow sensors

Finding the right flow sensor (SFM) for your medical ventilation or high flow device.
Our flow sensor portfolio offers a comprehensive range of gas flow sensors optimized for medical
applications. The SFM product range is specifically engineered for medical ventilation, addresses all
relevant flow monitoring requirements and is organized in three families, depending on the position of
the sensor in the ventilation system:
1.
2.
3.

Inspiratory
Expiratory
Proximal

The figure below provides a first guideline to select a suitable sensor depending on the beforementioned
position in the application.

In addition, some sensors offer unique features and characteristics that may be considered during sensor
selection. These features are summarized in the following while the table on page 4-6 provides acomprehensive overview.

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1. Inspiratory flow sensors

Our inspiratory flow sensors are typically used inside the ventilator to measure the individual
air/O2/heliox gas lines as well as the total flow of the mixed gas before delivery to the patient.
•Selection based on operating gage pressure 1•••> 1bar → SFM4300 (or SFM4200 for flows > 50slm)> 150mbar → SFM3013

Lower operating pressure: all other sensors (SFM3003 family, SFM3100, SFM3119 andSFM3200).

•Consider the following criteria according to your requirements to identify the most suitable sensor
in the table on page 4:
••
•
•
•
•

Form factor and size

Mechanical connection
Measured gases

Flow range and range of best performance (low or high flows)

Analog or digital output

Special features like gas NTC temperature sensor etc.

If you identify more than one sensor option, it is recommended to evaluate the sensor(s) in your device
as the specific device design can influence the measurement.

2. Proximal flow sensors

Gas flow sensors specifically designed to monitor flow in close proximity to the patient, where thefollowing main challenges have been resolved by our portfolio:•High humidity and condensation

All our proximal sensors are capable to measure saturated gas/air and feature a heater to prevent

condensation at the sensor’s chip, therefore ensuring continued accuracy.
•Contamination

We offer both single-use and washable sensors.

•Sensor handling by medical personnel

All our proximal sensors feature a mechanical interface allowing a clip-on connection, easy todisconnect and reconnect.

•Inspiration and expiration flow

All our proximal sensors allow bi-directional flow sensing.
•Individual sensor packaging for single-use sensors

Individual sensors are protected against contamination from their production until their use bycaregivers. Quality control is improved, supply chain management is simplified, and a customized

label brings all needed information to the users.

The selection of the right sensor is based on two main criteria••

Patient group: neonates or adults/pediatric

Use in clinical setting: single use/disposable or washable

1 Gage pressure describes the pressure difference between the gas pressure in the tubes / flow sensor and the ambient pressure© Copyright Sensirion AG, Switzerland

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3. Expiratory flow sensors

SFM3200-AW has been specifically designed for the expiratory position with a minimized pressure drop,
washability, a heater and the capability to measure vapor-saturated gas/air.
Alternative options•

Proximal sensors can be used further from the patient in expiratory position, in case a disposable

option is preferred.
•Inspiratory sensors can be placed in the expiratory position if measures are taken against

contamination (like HMF filters) and condensation (water traps). Inspiratory sensors are not designed
to be cleaned or disinfected and require non-condensing operating conditions.

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Form factor

SensorMeasured gases

Flow range [slm]Pressure drop
@flow[slm]Typ. accuracy

Recommended@flow[slm](allowed)[%m.v.]

supply voltage

Special features

Inspiratory flow sensors
Medical cones

SFM3003-CL-30 to +300

This form factor usually

SFM3003-CE-150 to +300

SFM3003-CET-150 to +300

22mm (ISO5356)
gives better accuracy at
higher flows

SFM3013-CL

• Air
• O2

• Air/O2 mixtures

Air/O2: -30 to +300
HeliOx: -30 to +200

SFM3013-CLM

SFM3019
SFM3020-30 to +300

-10 to +240
• Air
• O2

-10 to +160

• Air/O2 mixtures
SFM3200

formula provided

• Air
• O2

• Air/O2 mixtures

formula provided© Copyright Sensirion AG4/7-100 to +250

@60: 80Pa@200: ±2%@60: 100Pa@200: ±2.5%@60: 100Pa@200: ±2.5%@60: 80Pa@200: ±2%@200: 500Pa@200: 600Pa@200: 600Pa@200: 500Pa@60: 80Pa@200: ±2%

3.3V

• Low pressure drop

3.3V

• Extended negative flow range

3.3V• Extended negative flow range(2.7 - 5.5V)(2.7 - 5.5V)(2.7 - 5.5V)• NTC temperature sensor in gas path

3.3V

• Low pressure drop

(2.7 - 5.5V)• Higher pressure resistance up to 1bar

3.3V

• Higher pressure resistance up to 1bargaugegauge@200: 500Pa

Heliox: ±4.5%(2.7 - 5.5V)@60: 80Pa@200: ±2%

3.3V

• See successor SFM3003-300-CL@60: 80Pa@160: ±2%

5V

• Analog output 0.5 – 4.5V

@60: 100Pa@100: ±3%

5V

• See successor SFM3003-CL or CE@200: 500Pa@200: 500Pa@200: 750Pa(2.7 - 5.5V)• Additional HeliOx calibration

Form factorSensor

Measured gases

Compact

SFM3100-VC• Air• O2-24 to +240

• Air
• O2-10 to +240

This form factor usually

Flow range [slm]• Air/O2 mixtures
formula provided

gives better accuracy atlow flows/smaller offset

SFM3119• Air/ O2 mixtures

SFM4200

O-ring / Push-in Legris /

• Air
• O2

0 to 160• Air

0 to 20• Air/O2 mixtures
formula provided

Down-mount

SFM4300

• O2

• CO2

• N2O

• Mixtures© Copyright Sensirion AG

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0 to 50

Pressure drop
@flow[slm]@60: 300Pa@200: 1600Pa

Typ. accuracy

Recommended@flow[slm](allowed)[%m.v.]@60: 2.5%@60: 200Pa@100: 2%

@60: 2000Pa@80: 2.5%@200: 1600Pa@160: 9000Pa@20: 2500Pa@50: 10000Pa

supply voltage
5V(4.75 - 5.25V)

Special features• NTC temperature sensor in gas path
• Analog output 0.095 – 2.45V• See successor SFM3119 (digital)

3.3V• Digital output

5V• Air, O2(2.7 - 5.5V)• Down-mount only

• Operating pressures up to 8 bar@20: 2%@50: 4%

3.3V(3.0 - 5.5V)• Air, O2, CO2, N2O and mixtures up to20slm• Air, O2 and mixtures up to 50slm• High resolution 0.4sccm for 20slm
ranges• Operating pressures up to 7 bar

Form factorSensor

Measured gases

Flow range [slm]Pressure drop
@flow[slm]Typ. accuracy[%m.v.]@flow[slm]Recommended
supply voltage

Special features

5V• Bidirectional(allowed)

Expiratory flow sensors
Medical cones

SFM3200-AW

22mm (ISO5356-1)

• Air
• O2

-100 to +250

• Air/ O2 mixtures
formula provided@60: 100Pa@200: 750Pa@100: 3%

• Autoclavable & cleanable• Integrated heater to prevent condensation

Proximal flow sensors
SFM3300-D

Medical cones• Air• O2-250 to +250

• Air/ O2 mixtures
formula provided

22mm (ISO5356-1)

SFM3300-AW

SFM3304-D@200: 1400Pa@100: 3%5V

• See successor SFM3304-D for OEM projects• Suitable for adults and children• Single-use• Integrated heater to prevent condensation• Available in catalog distribution• Air• O2-250 to +250

• Air
• O2-250 to +250

• Air/ O2 mixtures
formula provided@60: 180Pa• Air/ O2 mixtures
formula provided@60: 180Pa@200: 1400Pa@60: 100Pa@200: 1150Pa@100: 3%5V

• Suitable for adults and children• Autoclavable & cleanable• Integrated heater to prevent condensation@100: 3%

3.3V

(3.15 - 3.45V)• Improved independence to inlet conditions• Suitable for adults and children• Single-use• Integrated heater to prevent condensation• Includes individual sensor packaging• Only available for OEM projects
SFM3400-D

15mm (ISO5356-1)

SFM3400-AW• Air• O2-33 to + 33

• Air
• O2-33 to + 33

• Air/ O2 mixtures
formula provided• Air/ O2 mixtures
formula provided© Copyright Sensirion AG

6/7@5: 100Pa@25: 900Pa@5: 100Pa@25: 900Pa@33: 3%5V• Suitable for neonates• Single-use• Integrated heater to prevent condensation• Suitable for neonates@33: 3%5V• Autoclavable & cleanable• Integrated heater to prevent condensation

Revision historyDateVersionJuly 2024

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