Yeah, I know what you're looking for, I was just trying to get a feel for the type of "pickup" you had, and the frequency range of the device.
Not knowing this, I'll throw a couple of things on the table. Yes, the device you're looking for can be designed.
The two bare wires sound inefficient to me. My wife has a pedometer with a heart rate monitor, it's a tranducer, the size of a dime, place your finger on on it and it has enough amplification to emit a loud beep with each heartbeat, probably enough power to transmit a foot or two (depends on the sensitivity of your receiver....cost $22.00 at radio shack....size, probably about 4 dimes stacked.
Other amplifiers/transmitters...a hearing aid...40 to 60 dB of gain...$11.00 on the internet. Polygraph machines have a number of transducers that could probably be obtained cheap.