Charge transfer sensing

While the transference of charge is an essential aspect of every capacitance sensor, a relatively new form of sensor makes overt use of the principle of charge conservation first deduced by Watson in the 1740s. Updated to use a microcontroller, mosfet switches, fet‐input opamps and band gap references, the principle of charge transference can be used to create an extremely sensitive and stable device with unique properties that transcend those of more pedestrian capacitance sensors. Also known as “QT” sensors, charge transfer sensors can have a dynamic range spanning many decades with noise floors in the sub‐femtofarad regime, allowing differential resolutions of mere fractions of a femtofarad. Such sensors are proving to have unique applications considered heretofore impossible, while also proving themselves as replacements for much more expensive sensing systems using photoelectric, acoustic, RF, and optical imaging techniques.