A method for performing chamber-to-chamber matching includes receiving a voltage and a current measured at an output of an RF generator of a first plasma system. The timing device and system, in accordance with the embodiments of the invention, comprise an electrochemical component which generates a visual andor audio indication of the passage of time. The apparatus includes one or more sensors that detect if the electrical source is miswired and operate one or more switches which preclude electrical continuity to one or more of the electrical lines of the appliance if a miswiring is detected. An analyzer receives the output signal of the acoustic receiver and provides an indication of at least one of stress and injury in the soft tissue based on the output signal.