A safe electrical connection between an integrated circuit and the human body is required for the recording of physiological signals such as electrocardiogram, electronystagmogram, and electromyogram signals. The recording chip is typically connected to the patient through a blocking capacitor, which prevents the flow of direct current in the event of circuit failure. However, in systems with a high integration density, blocking capacitors are inconvenient due to their large size and their effect on the signal transfer function. Therefore, this study proposes a fully integratable functional monitoring scheme which involves applying a test signal to the amplifier input and detecting its presence at the output. In the event of failure, the resulting change in the output voltage is detected and the chip can be switched into a safe state. Test signal addition and extraction circuits are proposed and analyzed. Measurement results are presented to confirm the correct operation in the context of a typical recording front-end.