I'm in need of flexible pressure sensors that can read how much force is exerted on someone's foot while running (these sensors would be placed inside the shoe). Since pressure can often be three times the weight of the person, I need something fairly strong. Are there fairly cheap sensors that are available or hacks that could do the same thing?
Thanks!
As you are presumably measuring changing (dynamic) loads, you could consider a piezo electric sensor.
At the simplest, use a piezo element usually sold as a buzzer (make sure you get the plain element with no electronics included, some 'buzzers' also have drive circuitry).
That will give you a voltage pulse proportional to applied pressure, which might give you the precision that you need, and is very small and light to insert in a shoe.
See this question for a similar solution (and the above image!)
Sensors such as you describe are usually called "Load Cell".
At the 600 pound weight, I haven't found any "flexible" load cells. A sensor would have to be quite robust.
Flexible might not be the best answer.
This load cell page has quite a range of load cells, several thousand pounds, also not very inexpensive.
This might be difficult to install in running shoes :
