A self-powered life monitor in a pocket-size, portable container including a casing with electrode probes mounted on the casing which are capable of piercing the skin to rest in subcutaneous tissue. The monitor further includes an amplifier electrically connected to the electrode probes and to a "life" indicator. The monitor is used by placing the electrode probes at different positions in an area of the human body where electrical potential is indicative of life activity, such as the areas of the heart or brain. The amplifiers enhance the difference between the electrical potentials measured by the probes, and the indicator indicates the existence and strength of the electrical potential and hence the presence or absence of life. For brain activity detection, a first embodiment (note particularly FIGS. 2 and 7) has supplemental, swing-out, pivoting electrodes, while a second embodiment (FIGS. 8 and 9) has supplemental, spring-out electrodes. Additionally a triangularly-shaped, extender electrode is used for heart activity detection (note FIGS. 1 and 4).