A Microcalorimeter for Nondestructive Analysis of Pacemakers and Pacemaker Batteries

A microcalorimeter has been built by the authors and used to measure internal losses in primary pacemaker batteries. Power dissipation of 10-50 μ W has been measured in new pacemaker batteries, much of which is traceable to innocuous exotherm from continuing curing of plastic materials in the battery. True internal shorts have produced 1000-2000 μ W of heat. Present noise level is about 3 μ W. A noise level of under 1 μ W should be achievable. Such a microcalorimeter should prove invaluable for nondestructive early identification of parasitic power losses, both in batteries and in completed pacemakers.