High input impedance D.C. amplifier for biomedical applications

The Biomedical Engineer knows the necessity and importance for a highly stable transistorized D.C. Amplifier with high input impedance, whenever he faces the problem of measuring physiological signals. This note describes a simple, easy to construct yet versatile, MOSFET input, transistorized D.C. Amplifier that has been successfully built and used in the measurement of bodyfluids such as pH of blood.