초록 ▼

A circuit for measuring the internal impedance of the cell of a heart pacer in order that the remaining life of the cell can be estimated. The test is performed by cutting off all current flow from the cell to the pacer circuitry, the pacer still being powered, however, by the conventional by-pass c

A circuit for measuring the internal impedance of the cell of a heart pacer in order that the remaining life of the cell can be estimated. The test is performed by cutting off all current flow from the cell to the pacer circuitry, the pacer still being powered, however, by the conventional by-pass capacitor. When the cell impedance test is conducted, a test capacitor is placed across the cell and it charges exponentially with a time constant which is a function of the cell impedance. By measuring the time required for the test capacitor potential to reach a reference level, the cell impedance can be ascertained. The measured parameter can be telemetered out of the pacer along with other data in the conventional manner. With a typical lithium iodide cell, the internal impedance of the cell varies from less than 100 ohms when new, to tens of kilohms near the end of the cell life.

대표청구항 ▼

A test system for ascertaining the remaining life of the battery of an implantable medical device by determining its internal impedance; said medical device including a battery, circuitry, and means for connecting said battery across said circuitry; the test system comprising test capacitor means; f

A test system for ascertaining the remaining life of the battery of an implantable medical device by determining its internal impedance; said medical device including a battery, circuitry, and means for connecting said battery across said circuitry; the test system comprising test capacitor means; first switch means for disconnecting said battery from across said circuitry; second switch means for connecting said battery across said test capacitor means; means for operating both of said first and second switch means simultaneously; means for comparing the potential across said test capacitor means with a reference level; and means for measuring the time interval required for the potential across said test capacitor means to reach said reference level while said first and second switch means are operated simultaneously.