Life signal detection using an on-chip split-ring based solid state microwave sensor

A technique for measuring the amplitude and frequency of breathing and heartbeat has been developed using an on-chip solid state sensor integrating a semiconductor microwave sensor and a split ring operating at a resonance frequency of 4.2 GHz. This technique allows the lock-in amplifier to make real-time measurements, analogous to measurements taken by a vector network analyser through an antenna, but with the advantage of being portable and having a user friendly DC output. The effectiveness of this approach is shown by performing several experiments to determine the breathing and heartbeat frequency with and without the presence of an obstacle between the test subject and the microwave sensor and transducer. The experimental results demonstrate the high sensitivity and large dynamic range over which the proposed system can be used for practical applications.