How to get an affordable respiration rate for the home lab of Physiologist Peter Gamma which is at the level of his professional medical & research grade education?

We have Peter Charltons Matlab respiratory rate estimation toolbox: https://www.mathworks.com/matlabcentral/fileexchange/55289-respiratory-rate-estimation PLUXBiosignals respiration belt Vernier Spirometers: https://www.vernier.com/product-category/?category=spirometers iWorx Spirometer: But unfortunately Peter Gamma still hasn’t found an affordable device to measure respiration rate for the home lab of Peter Gamma which is at the level of his professional education which is medical and research grade. So …