Capacitance sensors with asynchronous ring oscillator circuit and capacitance

摘要

A capacitance sensor comprises an asynchronous ring first in first out (FIFO) oscillator circuit having an electrode for receiving a sample for analysis. A sample placed into contact with the electrode causes a change in capacitance at the electrode which gives rise to a change in the oscillation frequency of the ring. This change in oscillation frequency can be used to identify the sample.