Best way to hook up Many analogue sensors
It seems that the sensor is highly non-linear and this is good in our case. 

You can try to connect these sensors to the digital inputs of the RaPi, if they have some hysteresis (AFAIK, the GPIO inputs have a hysteresis). The schematic if the following:







simulate this circuit &ndash; Schematic created using CircuitLab

The value of R1 is the same as the resistance of the sensor on the threshold point. Determine it experimentally.

The capacitor C1 is to reduce the induced EMI. One approximate value is 100nF but it may vary. 

Mount the resistors and capacitors as close to the CPU board as possible. Use shielded cable (low frequency) to connect the sensors. The shield must be the ground wire. 

If the EMI are too big, some software processing of the false positives can be made. 

If RaPi has no enough inputs (80) you should make some multiplexing. Note, that in this case, some buffers with hysteresis have to be used - 74HC7540 is good choice. You can use 10 of them and connect all outputs together and control the 3-rd state inputs by GPIO outputs. This way with 10 outputs and 8 inputs you can control 80 pressure sensors.