air flow sensor

[totti]

Hi all,
I'm involved in building a medical device which requires a sensor to measure the flow of breathing. In similar devices, pneumotachometers are used. The problem is pneumotachometers are very sensitive with the gas's composition which is changed during the operation. The error is significant. Can any body recommend other types of sensors to measure the flow?
Thank you very much,

 

[cbarn24050]

Hi, hot thermistor is the usual way.

 

[skills]

If you are really interested in measuring the mass flow, you could as was suggested, emulate a MAF or MASS AIR FLOW as is used in automotive systems to measure the mass of air intake. It uses a hot wire that has a thermister directly adjacent to it. A current it flowing in it to maintain a temperature of say 115 degrees. The current is measured to determine the mass of air flow through chamber. I don't have a source right now for these , I look into it.

 

[totti]

Thank you very much for your advices. I appreciate that.