Repairing the hand:

• Index finger is still not acting right.  Tried replacing the bottom just to get exactly the same resistance as before which is equal to the other working ones.
• Replaced top one again.  Still 100 ohms too high.  Think this might be due to a groove in the metal.
• Smoothed out the metal and put insulating layer on it.

Computer Controlled Amplifier:

• Came across this website listing various amplifiers:  http://www.datasheetcatalog.com/function/Analog_and_Mixed-Signal_Devices/Signal_amplification/Audio_amplifiers.shtml
• The one that looks good for our purposes is:  1 W BTL audio amplifier with digital volume control TDA8551
• This IC is controlled by a trinary input(3 signals)
• High signal is between 4.2-5 volts
• Float signal is between 1-3.4 volts
• Low signal is between 0-.6 volts
• I was able to get these 3 signals using the i2c rheostats we have in combination with 500 ohms of resistance.  The power from the i2c adapter is connected to b1 with 500 ohms resistance and then w1 is connected to ground.  The voltage is divided at b1 so the signal is between Vdd and b1.
• The mode is also controlled by a trinary input so one i2c rheostat chip(which has 2 rheostats in it) will control 1 amplifier using the two rheostats for each input.
• We can only have 4 of these on one i2c bus so the fifth finger will need another usb-i2c adapter.

Calculating R2 for voltage divider:

R1 = 500 ohm

Vin = 5

Vout = x (desired output voltage)