I need it to be compact so programming seems ideal.
A PIC solution might work...any suggestions?
Any other processor is fine also.
No, I can't use a light theremin...
And no, I can't use Harrison Instruments' because its too big and too many connections.
If possible, then this is to be used on fruit flies to see how much activity they do when foreign substances are added. Again, if possible if a PIC solution is used, then can the PIC detect when the flies move because they change an oscillation. Most likely I will wind a coil and place it in the jar and then have it detect. The best way would be to use the PIC to print an output via some sort of display so that the scientific results can be tested.