4PCS Thin Film Pressure Sensor

yes they were perfect , very sensitive , very high impedance, when no pressure is applied . very happy

It would be nice if the manufacturer had published links to sketches for these. However, you can search yourself and find examples from the likes of Adafruit and others. Fairly good linearity in response curve, but again, you aren't going to force calculation, but merely approximation or presence of a force change. For our use, we needed to detect when someone sat in a chair and also when they got up. These devices aren't really meant to detect the weight of a human body, but they do just fine as we found. Good price... two mylar packs with two sensors in each pack.

One of the pack of four I bought did not work.

A little smaller in diameyer than they appear, but worked well enough. I don't know enough about them to really order the correct item, just taking a shot in the dark and guessing at the specs