Dear Fernando,

I don't have experience with this kind of measurement, but, as this is a very low frequency

Hi Luciano! Thank you for your answer.

I think pressure sensors are also viable, but I've seen in the literature that accelerometers fixed to the patient's waist are recommended.

Abs,

Fernando

Dear Fernando,

for low frequency measurements, velocimetric sensors are better than accelerometric sensors. At the same time, if you want to use an accelerometric sensor, I suggest you a force-balance sensor.

For any question, do not esitate to contact me.

Sincerely,

Rocco

Thank you Rocco!

Which velocimetric sensors and force-balance sensors do you recommend, please?

A good compromise could be the instrumentation produced by the Sara Electronic Instruments (http://www.sara.pg.it/index.php/geofisica-2/?lang=en)

Rocco

Dear Fernando

most newer mobile devices and tablets have built-in accelerometers and gyroscopes and as you move the physical hardware, the changes in the orientation of the device and acceleration are detected by the browser which are then mapped into a waveform that can measure very well the respiratory rate. Try by yourself putting on your chest a mobile that has an app like this https://play.google.com/store/apps/details?id=kr.sira.vibration&hl=en

Alessandro

Hi Alessandro, thank you very much for your answer. The app you told me is very interesting, but is not useful for my needs, since I cannot access and manipulate the displayed signal. Besides, I would prefer measuring the respiratory rate with a sepparate device, so that the phone is in another physical location. Do you happen to know any app that allows me to have access to the measured data? Your help is very much appreciated, thank you very much!

Dear Fernando, you are right the app above is not recording the signal. Try in Google play to install Seismic Record and you will get the data on your phone. I think it shoul be easy with another app to count wavelengths in 60s to get the breath frequency. I will try by myself and let you know. 

Another option is to buy a qcn sensor and join the program  http://www.emsc-csem.org/service/QCN/ . The sensor kit costs 44$ and will send the recorded motion to a tablet or computer where you are allowed to process data