small force sensors

Searching on "load cells" or "strain gauges" might work. (I don't think piezo is quite the right concept.)

Describe better your application as force magnitude, uncertainty level and available space. If you come within some limits it is possible to suggest even 0.5 mm sensors. If for you piezo is a quartz sensor (or similar) then it is totally not usable since it is operational ONLY with high dynamic loads. This is related to the physics of "piezo" electricity. If you think "piezo" resistive sensor they can be used for low dynamics as well.

Thanks for the comments and redirection. I'm looking for multiple force sensors that one could apply to the palm of the hand (or glove) or insert in shoes to measure forces applied while lifting weight OR while running. As well, small enough and wide enough to measure the impact applied acros a shoulder pad or a knee pad in a sporting event.

Look at TEKSCAN they have a sensor exactly for what you want to do it is a thin shhet sensor FLEXIFORCE.

This may be a little late in the game, but you may also want to try some FSR sensors. Interlink makes those and I think you can find them on DigiKey for cheap.