demodulating a modulated signal externally supplied to {TAIL ~ said first electrode} in {HEAD ~ the first liquid container} 
demodulating a modulated signal externally supplied to { TAIL ~ said first electrode } in { HEAD ~ the first liquid container }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD